Methods for fabricating appliances from polymerizable compositions

ABSTRACT

Methods for fabricating orthodontic appliances are provided. In some embodiments, a method includes providing a polymerizable composition including a first polymerizable component and a second polymerizable component. The polymerizable composition can be characterized by an initial ratio of the first polymerizable component to the second polymerizable component. The method can include fabricating a portion of the orthodontic appliance from the polymerizable composition by forming a first region of the orthodontic appliance by exposing the polymerizable composition to radiation, the first region including a first ratio of the first polymerizable component to the second polymerizable component. The method can also include forming a second region of the orthodontic appliance, the second region including a second ratio of the first polymerizable component to the second polymerizable component. The initial ratio, the first ratio, and the second ratio can be different.

CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No.17/034,869, filed Sep. 28, 2020, which is a continuation of U.S. patentapplication Ser. No. 16/667,556, filed Oct. 29, 2019, now U.S. Pat. No.10,788,753, issued Sep. 29, 2020, which is a continuation of U.S. patentapplication Ser. No. 16/024,555, filed Jun. 29, 2018, now U.S. Pat. No.10,495,973, issued Dec. 3, 2019, which claims the benefit of U.S.Provisional Application No. 62/527,749, filed Jun. 30, 2017, which areincorporated herein by reference in their entirety for all purposes.

BACKGROUND

Orthodontic procedures typically involve repositioning a patient's teethto a desired arrangement in order to correct malocclusions and/orimprove aesthetics. To achieve these objectives, orthodontic appliancessuch as braces, retainers, shell aligners, and the like can be appliedto the patient's teeth by an orthodontic practitioner. The appliance isconfigured to exert force on one or more teeth in order to effectdesired tooth movements. The application of force can be periodicallyadjusted by the practitioner (e.g., by altering the appliance or usingdifferent types of appliances) in order to incrementally reposition theteeth to a desired arrangement. There remains a need for improved dentalappliance fabrication.

SUMMARY

The present disclosure provides methods, systems, and devices for thegeneration of composite materials from a single resin using lightexposure.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter, nor is it intended to be used as an aid indetermining the scope of the claimed subject matter.

In various aspects, the present disclosure provides a process for makinga composite polymer composition, said process comprising the steps of:providing a light polymerizable liquid composition comprising a firstpolymerizable component, a second polymerizable component, and aphotoinitiator, wherein the light polymerizable liquid composition ischaracterized by a liquid ratio of the first polymerizable component tothe second polymerizable component; generating a first polymer regionhaving a first ratio of the first polymerizable component to the secondpolymerizable component by exposing the light polymerizable liquidcomposition to a first exposure of light characterized by a firstexposure region; and polymerizing the light polymerizable liquidcomposition in a second region different than the first region andadjacent to, contacting, or overlapping with the first exposure region,wherein the second region has a second ratio of the first polymerizablecomponent to the second polymerizable component, and wherein the liquidratio, the first ratio, and the second ratio are different.

In some aspects, the light polymerizable liquid composition ishomogenous. In certain aspects, the liquid ratio has a variation, andthe variation is dependent on localization. In certain aspects, thefirst polymerizable component can diffuse freely through the lightpolymerizable liquid composition. In some aspects, the secondpolymerizable component can diffuse freely through the lightpolymerizable liquid composition.

In certain aspects, the first ratio is greater than the liquid ratio,and the liquid ratio is greater than the second ratio. In some aspects,the first ratio is greater than the second ratio, and the second ratiois greater than the liquid ratio. In certain aspects, the second ratiois greater than the liquid ratio, and the liquid ratio is greater thanthe first ratio. In some aspects, the second ratio is greater than thefirst ratio, and the first ratio is greater than the liquid ratio. Incertain aspects, the liquid ratio is greater than the first ratio, andthe first ratio is greater than the second ratio. In some aspects, theliquid ratio is greater than the second ratio, and the second ratio isgreater than the first ratio.

In some aspects, polymerizing the light polymerizable liquid compositionin the second region generates a second polymer, and wherein the firstpolymer is characterized by one or more different polymer propertiesthan said second polymer. In certain aspects, the one or more differentpolymer properties are selected from the group consisting of: Tg,storage modulus, Young's modulus, elongation to break, elongation toyield, or any combination of these.

In certain aspects, the first polymer is characterized by a Tg that isfrom 2° C. to 50° C. greater than the second polymer from 5° C. to 50°C. greater than the second polymer, from 5° C. to 40° C. greater thanthe second polymer, from 5° C. to 30° C. greater than the secondpolymer, from 5° C. to 20° C. greater than the second polymer, from 5°C. to 10° C. greater than the second polymer, from 10° C. to 20° C.greater than the second polymer, from 10° C. to 50° C. greater than thesecond polymer, from 10° C. to 100° C. greater than the second polymer,from 1° C. to 100° C. greater than the second polymer, from 1° C. to500° C. greater than the second polymer, from 10° C. to 500° C. greaterthan the second polymer, from 1° C. to 50° C. greater than the secondpolymer, from 1° C. to 40° C. greater than the second polymer, from 1°C. to 30° C. greater than the second polymer, from 1° C. to 20° C.greater than the second polymer, from 1° C. to 10° C. greater than thesecond polymer, or from 1° C. to 5° C. greater than the second polymer.

In some aspects, the first polymer is characterized by a storage modulusthat is from 1 MPa to 1,000 MPa greater than the second polymer, from 1MPa to 500 MPa greater than the second polymer, from 1 MPa to 250 MPagreater than the second polymer, from 1 MPa to 200 MPa greater than thesecond polymer, from 1 MPa to 100 MPa greater than the second polymer,from 1 MPa to 50 MPa greater than the second polymer, from 1 MPa to 10MPa greater than the second polymer, from 50 MPa to 200 MPa greater thanthe second polymer, from 50 MPa to 500 MPa greater than the secondpolymer, from 50 MPa to 1,000 MPa greater than the second polymer, from100 MPa to 1,000 MPa greater than the second polymer, from 200 MPa to400 MPa greater than the second polymer, from 200 MPa to 600 MPa greaterthan the second polymer, from 200 MPa to 1,000 MPa greater than thesecond polymer, or from 200 MPa to 2,000 MPa greater than the secondpolymer.

In certain aspects, the first polymer is characterized by an elongationto break that is from 10% to 1,000% greater than the elongation to breakof the second polymer, from 10% to 500% greater than the elongation tobreak of the second polymer, from 10% to 100% greater than theelongation to break of the second polymer, from 10% to 50% greater thanthe elongation to break of the second polymer, from 20% to 1,000%greater than the elongation to break of the second polymer, from 30% to1,000% greater than the elongation to break of the second polymer, from50% to 1,000% greater than the elongation to break of the secondpolymer, or from 100% to 1,000% greater than the elongation to break ofthe second polymer.

In some aspects, the step of exposing said light polymerizable liquidcomposition to said first exposure results in a polymerization inducedphase separation in said light polymerizable liquid composition alongone or more lateral directions. In certain aspects, the firstpolymerizable component and said second polymerizable component aremiscible in each other. In some aspects, the second polymerizablecomponent is partially or fully immiscible in the first polymer. In someaspects the first polymerizable component and said second polymerizablecomponent are monofunctional monomers, polyfunctional monomers or acombination of these.

In certain aspects, the first polymerizable component comprises one ormore of a methacrylate monomer, an acrylate monomer, a thiol monomer, avinyl acetate derivative monomer, a styrene monomer, a vinyl ethermonomer or a combination of these; and wherein said second polymerizablecomponent comprises one or more of an acrylate monomer, a thiol monomer,an allyl ether monomer, a vinyl acetate derivative monomer, a vinylchloride monomer, an acrylonitrile monomer, a vinyl ether monomer, avinyl silane (or siloxane) monomer, a butadiene monomer, a norbornene, amaleate monomer, a fumarate monomer, an epoxide monomer, an anhydridemonomer, an hydroxyl monomer a combination of these.

In some aspects the first polymerizable component is provided in saidlight polymerizable liquid composition at a concentration selected overthe range 10 to 90 wt % and said second polymerizable component isprovided in said light polymerizable liquid composition at aconcentration selected over the range 10 to 90 wt %.

In certain aspects, the light polymerizable liquid composition furthercomprises one or more additives selected from the group consisting ofadditional polymerizable components, additional photoinitiators, thermalinitiators, polymerization catalysts, surfactants, dispersants,viscosity modifiers, pigments, dyes, surface active compounds, fillers,particles, binders, or any combination of these.

In some aspects the first polymer, the second polymer, or both areformed by a free radical polymerization, ionic polymerization (cationicor anionic) or a combination of these. In certain aspects, the firstpolymer is primarily formed by free radical polymerization and whereinthe second polymer is primarily formed by ionic polymerization (cationicor anionic). In some aspects, the first polymer is primarily formed byfrom photo-induced polymerization and wherein the second polymer isprimarily formed by thermally induced polymerization.

In some aspects, the first polymerizable component and said secondpolymerizable component are characterized by a reactivity ratio greaterthan or equal to 1. In some aspects, the reactivity ratio is selectedover the range of 1 to 10. In certain aspects, the reactivity ratioresults from differences in a polymerization rate coefficient,concentration, functionality or any combination of these of said firstpolymerizable component and said second polymerizable component. In someaspects, the reactivity ratio results from differences in the solubilityor diffusivity of said first polymerizable component and said secondpolymerizable component. In certain aspects, the reactivity ratioresults from differences in oxygen inhibition, light absorption,photoinitiator concentration or any combination of these for saidself-polymerization reaction of the first polymerizable component andsaid polymerization reaction of the first polymerizable component andthe second polymerizable component.

In certain aspects, the first polymerizable component and said secondpolymerizable component each independently are characterized by adiffusivity in said light polymerizable liquid sufficient for a director additive manufacture process. In some aspects, at least a portion ofsaid first exposure region, said second region or both independentlyhave at least one lateral dimension less than or equal to 100 μm. Insome aspects, at least a portion of said first exposure region, saidsecond region, or both independently have at least one lateral dimensionof 50 μm to 100 nm. In certain aspects, the first exposure regioncomprises more than one first exposure area or wherein said secondregion comprises more than one second exposure area. In some aspects,the first exposure region is characterized by a light intensity of lessthan 20 mW/cm²; and wherein the second region is characterized by alight intensity equal to or greater than the light intensity of thefirst exposure region.

In some aspects, the first exposure region is exposed to light more thanonce before the second region is exposed to light. In certain aspects,the first exposure is generated via laser exposure, holography, DLPprojection, optical lithography, pulsed light or a combination of these.In certain aspects, the step of polymerizing said light polymerizableliquid composition comprises exposing said light polymerizable liquidcomposition to a second exposure of light. In some aspects, the step ofpolymerizing said light polymerizable liquid composition characterizedby the second region comprises exposing said light polymerizable liquidto thermal energy.

In various aspects, the process for making a composite polymercomposition further comprises a method of direct or additivefabrication. In some aspects, the method of direct or additivefabrication uses a single light polymerizable liquid composition. Incertain aspects, the method of direct or additive fabrication isselected from the group consisting of: a stereolithographic (SLA)technique, a digital light processing (DLP) technique, a continuousliquid interface production technique, a micro-stereolithographic(μ-SLA) technique, a two photon polymerization technique, a materialjetting technique, and a combination thereof. In some aspects, themethod of direct or additive fabrication generates said polymercomposition comprising a composite material. In certain aspects, themethod of direct or additive fabrication generates an orthodonticappliance comprising the polymer composition. In some aspects, after thesecond exposure is complete, a new layer is started. In certain aspects,one of more of the layers uses only 1 exposure for that layer.

In various aspects, the present disclosure provides a method of making acomposite polymer composition from a single resin, the processcomprising the steps of: providing a resin, the resin comprising a firstmonomer component and a second monomer component, the resincharacterized by a resin ratio of the first monomer component to thesecond monomer component; initiating a polymerization reaction byexposing the resin to a first exposure of light; forming a first regionhaving a first ratio of the first monomer component to the secondmonomer component; and forming a second region having a second ratio ofthe first monomer component to the second monomer component, wherein theresin ratio, the first ratio, and the second ratio are different.

In some aspects, the first ratio is greater than the resin ratio, andthe resin ratio is greater than the second ratio. In certain aspects,the first ratio is greater than the second ratio, and the second ratiois greater than the resin ratio. In some aspects, the second ratio isgreater than the resin ratio, and the liquid ratio is greater than thefirst ratio. In certain aspects, the second ratio is greater than thefirst ratio, and the first ratio is greater than the resin ratio. Insome aspects, the resin ratio is greater than the first ratio, and thefirst ratio is greater than the second ratio.

In some aspects, the method further comprises the step of polymerizingthe second monomer component. In some aspects, initiating thepolymerization reaction comprises exposing the resin to a source ofradiation. In certain aspects, an object is placed between the firstregion and the source of radiation. In some aspects, the objectcomprises a mask, a cover, a lens, a filter, or any combination thereof.In certain aspects, the source of radiation comprises ultraviolet light,visible light, infrared light, microwave irradiation, laser exposure,holography, DLP projection, optical lithography, pulsed light, or acombination thereof.

In certain aspects, the polymerization of the first monomer componentforms a first polymer. In some aspects, polymerizing the second monomercomponent forms a second polymer. In certain aspects, the polymerizationreaction results in a polymerization-induced phase separation along oneor more lateral directions. In certain aspects, the first region and thesecond region are separated by a concentration gradient. In someaspects, the concentration gradient comprises the concentrations of thefirst monomer component and the second monomer component. In certainaspects, the concentration gradient comprises the concentration of thefirst polymer and the second polymer. In some aspects, the methodfurther comprises the step of using a mask to selectively define thefirst region or the second region.

In some aspects, the polymerization of the second monomer component usesa secondary photopolymerization. In certain aspects, the secondaryphotopolymerization comprises the use of a mask, an overlapping region,a full blanket exposure, or a combination thereof. In some aspects, thesecondary photopolymerization uses a second source of radiation, saidsource of radiation comprising ultraviolet light, visible light,infrared light, microwave irradiation, or a combination thereof. Incertain aspects, the polymerization of the first monomer and thepolymerization of the second monomer use the same source of radiation.

In certain aspects, the first monomer component and the second monomercomponent are miscible. In some aspects, the first monomer component andthe second monomer component are fully miscible. In certain aspects, thesecond monomer component is immiscible in the first polymer. In someaspects, the second monomer component is fully immiscible in the firstpolymer. In certain aspects, the first monomer component is immisciblein the first polymer. In some aspects, the first monomer component isfully immiscible in the first polymer.

In some aspects, the first monomer component is monofunctional,polyfunctional, or a combination thereof. In certain aspects, the secondmonomer component is monofunctional, polyfunctional, or a combinationthereof. In some aspects, the first monomer component comprises one ormore of a methacrylate monomer, an acrylate monomer, a thiol monomer, avinyl acetate monomer, a styrene monomer, a vinyl ether monomer, aderivative thereof, or a combination thereof. In certain aspects, thesecond monomer component comprises one or more of an acrylate monomer, athiol monomer, an allyl ether monomer, a vinyl acetate monomer, a vinylchloride monomer, an acrylonitrile monomer, a vinyl ether monomer, avinyl silane (or siloxane) monomer, a butadiene monomer, a norbornene, amaleate monomer, a fumarate monomer, an epoxide monomer, an anhydridemonomer, a hydroxyl monomer, a derivative thereof, or a combinationthereof.

In certain aspects, from 10 to 90 wt % of the resin consists of thefirst monomer component. In some aspects, from 10 to 90 wt % of theresin consists of the second monomer component. In certain aspects, theresin further comprises an additive. In some aspects, the additive isselected from the group consisting of a polymerizable component, aphotoinitiator, a thermal initiator, a polymerization catalyst, asurfactant, a dispersant, a viscosity modifier, an optical absorber, apigment, a dye, a surface active compound, a filler, a particle, abinder, or any combination thereof.

In some aspects, the polymerization reaction comprises ionicpolymerization, free radical polymerization, or a combination thereof.In certain aspects, the ionic polymerization comprises cationicpolymerization, anionic polymerization, or a combination thereof. Insome aspects, the first polymer is formed by free radicalpolymerization, ionic polymerization, photo-initiated polymerization,thermally induced polymerization, or a combination thereof. In certainaspects, the second polymer is formed by free radical polymerization,ionic polymerization, photo-initiated polymerization, thermally inducedpolymerization, or a combination thereof. In some aspects, greater than50% of the first polymer is formed by free radical polymerization. Incertain aspects, greater than 50% of the second polymer is formed byionic polymerization. In some aspects, the ionic polymerizationcomprises cationic polymerization, anionic polymerization, or acombination thereof. In certain aspects, greater than 50% of the firstpolymer is formed by photo-initiated polymerization. In some aspects,greater than 50% of the second polymer is formed by thermally inducedpolymerization. In certain aspects, greater than 50% of the firstpolymer is formed by thermally induced polymerization. In some aspects,greater than 50% of the second polymer is formed by photo-initiatedpolymerization.

In certain aspects, the first monomer component and the second monomercomponent have a ratio of reactivity, and wherein the ratio ofreactivity of the first monomer component to the second monomercomponent is from 1:1 to 1:10,000, from 1:1 to 1:5,000, from 1:1 to1:2,500, from 1:1 to 1:1,000, from 1:1 to 1:500, from 1:1 to 1:100, from1:1 to 1:50, from 1:1 to 1:30, from 1:1 to 1:20, from 1:1.5 to 1:10,000,from 1:1.5 to 1:5,000, from 1:1.5 to 1:2,500, from 1:1.5 to 1:1,000,from 1:1.5 to 1:500, from 1:1.5 to 1:100, from 1:1.5 to 1:50, from 1:1.5to 1:30, from 1:1.5 to 1:20, from 1:5 to 1:10,000, from 1:5 to 1:5,000,from 1:5 to 1:2,500, from 1:5 to 1:1,000, from 1:5 to 1:500, from 1:5 to1:100, from 1:5 to 1:50, from 1:5 to 1:30, from 1:5 to 1:20, from 1:10to 1:10,000, from 1:10 to 1:5,000, from 1:10 to 1:2,500, from 1:10 to1:1,000, from 1:10 to 1:500, from 1:10 to 1:100, from 1:10 to 1:50, from1:10 to 1:30, or from 1:10 to 1:20. In some aspects, the first monomercomponent is from 1-fold to 10-fold more reactive than the secondmonomer component. In certain aspects, the first monomer component isfrom 1-fold to 1000-fold, from 1-fold to 500-fold, from 1-fold to100-fold, from 1-fold to 50-fold, from 1-fold to 10-fold, from 2-fold to1000-fold, from 2-fold to 500-fold, from 2-fold to 100-fold, from 2-foldto 50-fold, from 2-fold to 10-fold, from 3-fold to 1000-fold, from3-fold to 500-fold, from 3-fold to 100-fold, from 3-fold to 50-fold,from 3-fold to 10-fold, from 5-fold to 1000-fold, from 5-fold to500-fold, from 5-fold to 100-fold, from 5-fold to 50-fold, from 5-foldto 10-fold, from 10-fold to 1000-fold, from 10-fold to 500-fold, from10-fold to 100-fold, from 10-fold to 50-fold, from 50-fold to 1000-fold,from 50-fold to 500-fold, from 50-fold to 100-fold, or from 100-fold to1000-fold more reactive than the second monomer component. In certainaspects, the first monomer component is 2-fold to 5-fold more reactivethan the second monomer component.

In certain aspects, the difference in the reactivity of the firstmonomer component and the reactivity of the second monomer componentcomprises a difference in a polymerization rate coefficient, adifference in concentration, a difference in functionality, a differencein solubility, a difference in diffusivity of the first monomercomponent, a difference in diffusivity of the second monomer component,or any combination thereof. In some aspects, the difference in thereactivity of the first monomer component and the reactivity of thesecond monomer component comprises a difference in oxygen inhibition, adifference in light absorption, a difference in photoinitatorconcentration, or a combination thereof.

In some aspects, the first monomer component and the second monomercomponent comprise a diffusivity in the resin sufficient for direct oradditive manufacturing. In certain aspects, the first region has atleast one lateral dimension less than or equal to 500 μm, less than orequal to 300 μm, less than or equal to 200 μm, less than or equal to 100μm, less than or equal to 50 μm, or less than or equal to 20 μm. In someaspects, the second region has at least one lateral dimension less thanor equal to 500 μm, less than or equal to 300 μm, less than or equal to200 μm, less than or equal to 100 μm, less than or equal to 50 μm, orless than or equal to 20 μm. In certain aspects, the first region has atleast one lateral dimension between 50 μm and 100 nm, between 50 μm and250 μm, between 100 μm and 250 μm, or between 100 μm and 500 μm. In someaspects, the second region has at least one lateral dimension between 50μm and 100 nm, between 50 μm and 250 μm, between 100 μm and 250 μm, orbetween 100 μm and 500 μm.

In certain aspects, the source of radiation initiates polymerization ofthe first monomer component in a first exposure region. In some aspects,the source of radiation initiates polymerization of the second monomercomponent in a second exposure region. In certain aspects, the firstexposure region comprises a plurality of first exposure areas, orwherein the second exposure region comprises a plurality of secondexposure areas. In some aspects, the first exposure region is exposed toa first light intensity of less than 20 mW/cm². In certain aspects, thesecond exposure region is exposed to a second light intensity, andwherein the second light intensity is equal to or greater than the firstlight intensity.

In some aspects, the first exposure region is exposed to the source ofradiation before the second exposure region is exposed to the source ofradiation. In certain aspects, the first exposure region is exposed tothe source of radiation more than once before the second exposure regionis exposed to the source of radiation. In some aspects, the source ofradiation comprises a wavelength of between 300 nm and 900 nm, between300 nm and 800 nm, between 300 nm and 700 nm, between 300 nm and 600 nm,between 300 nm and 500 nm, between 300 nm and 450 nm, between 300 nm and400 nm, between 400 nm and 800 nm, between 350 nm and 800 nm, between350 nm and 600 nm, or between 350 nm and 500 nm. In some aspects, thefirst exposure region is exposed to laser exposure, holography, DLPprojection, optical lithography, pulsed light, or a combination thereof.In certain aspects, the second exposure region is exposed to laserexposure, holography, DLP projection, optical lithography, pulsed light,or a combination thereof. In certain aspects, at least one of the firstexposure region and the second exposure region are exposed to more thanone exposure of light. In some aspects, the second exposure region isexposed to thermal energy.

In various aspects, the method of making a composite polymer compositionfrom a single resin further comprises the step of using a singleadditive manufacturing machine. In certain aspects, the single additivemanufacturing machine comprises a 3D printer.

In various aspects, the method of making a composite polymer compositionfrom a single resin further comprises the step of fabricating thecomposite polymer composition using additive fabrication or directfabrication. In some aspects, the additive fabrication and/or the directfabrication uses a single light polymerizable liquid composition. Insome aspects, the additive fabrication and/or the direct fabricationcomprises a stereolithographic (SLA) technique, a digital lightprocessing (DLP) technique, a continuous liquid interface productiontechnique, a micro-stereolithographic (μ-SLA) technique, a two photonpolymerization technique, a material jetting technique, or a combinationthereof.

In certain aspects, a new layer is started after the second exposureregion is exposed to the source of radiation. In some aspects, one ormore regions use a single exposure of radiation. In certain aspects, thecomposite polymer composition comprises an orthodontic appliance.

In some aspects, the first region has a vertical dimension less than orequal to 500 μm, less than or equal to 300 μm, less than or equal to 200μm, less than or equal to 100 μm, less than or equal to 50 μm, or lessthan or equal to 20 μm. In certain aspects, the second region has avertical dimension less than or equal to 500 μm, less than or equal to300 μm, less than or equal to 200 μm, less than or equal to 100 μm, lessthan or equal to 50 μm, or less than or equal to 20 am. In some aspects,the first region has a vertical dimension between 50 μm and 100 nm,between 50 μm and 250 μm, between 100 μm and 250 μm, or between 100 μmand 500 μm. In certain aspects, the second region has a verticaldimension between 50 μm and 100 nm, between 50 μm and 250 μm, between100 μm and 250 μm, or between 100 μm and 500 μm.

In certain aspects, the resin is homogenous. In other aspects, the resinratio has a variation, and the variation is dependent on localization.In some aspects, the first polymerizable component can diffuse freelythrough the resin. In certain aspects, the second polymerizablecomponent can diffuse freely through the resin.

In various aspects, the present disclosure provides a composite materialmade by any one of the disclosed methods. In certain aspects, the firstpolymer comprises a storage modulus at least 200 MPa greater than thestorage modulus of the second polymer. In some aspects, the firstpolymer comprises a fracture strain that is from 10% to 1,000% greaterthan the elongation to break of the second polymer, from 10% to 500%greater than the elongation to break of the second polymer, from 10% to100% greater than the elongation to break of the second polymer, from10% to 50% greater than the elongation to break of the second polymer,from 20% to 1,000% greater than the elongation to break of the secondpolymer, from 30% to 1,000% greater than the elongation to break of thesecond polymer, from 50% to 1,000% greater than the elongation to breakof the second polymer, or from 100% to 1,000% greater than theelongation to break of the second polymer.

In some aspects, the strength of the composite material is greater thanthat of the first polymer or the second polymer. In certain aspects, theflexibility of the composite material is greater than that of the firstpolymer or the second polymer.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an exemplary dental appliance that can be formed usingcomposite materials disclosed herein.

FIG. 2 depicts the cross-section of the dental appliance from FIG. 1 .

FIG. 3 provides a legend for the materials of the layers described inFIGS. 4-7 .

FIG. 4 depicts the formation of the first layer of a composite material,and depicts the first exposure for the second layer of a compositematerial.

FIG. 5 depicts the second exposure for the second layer of a compositematerial, the first exposure of the third layer of a composite material,and the second exposure of the third layer of a composite material.

FIG. 6 depicts the formation of layers 4, 5, and 6 of a compositematerial, including the use of a lower light intensity to create thesixth layer, resulting in the formation of a gradient in the Z-axis.

FIG. 7 depicts the lateral dimensions and vertical dimension as usedherein.

FIG. 8A depicts the optical image and inset Raman map of a sampleirradiated using a 5_10 mask.

FIG. 8B depicts the optical image and inset Raman map of a sampleirradiated using a direct interference pattern from a laser.

FIG. 9A depicts dogbone patterning for creating a masked exposure.

FIG. 9B depicts results of a tensile test wherein the composition ishomogenous.

FIG. 9C depicts results of a tensile test wherein the compositioncomprises selectively polymerized lines parallel to the long axis of thedogbone component.

FIG. 9D depicts results of a tensile test wherein the compositioncomprises selectively polymerized lines perpendicular to the long axisof the dogbone component.

DETAILED DESCRIPTION

The present disclosure relates to methods, systems, devices, and kitsfor creating composite materials from a single resin. More specifically,in some aspects, the present disclosure relates to methods, systems,devices, and kits for forming composite materials having structure,wherein the structure is generated using 3D printing techniques andlight exposure. In certain aspects, the methods utilize diffusionbetween a first region undergoing a polymerization reaction, wherein onemonomer component is preferentially polymerized, and a second regionwherein the monomer component less polymerized. In certain embodiments,the first region is a three-dimensional space. In some embodiments, thesecond region is a three-dimensional space. In preferred embodiments,the first region is defined by a 3 dimensional X,Y,Z-space. In anotherembodiment, the second region is defined by a 3 dimensional X,Y,Z-space.

In certain embodiments, the first region has an aspect ratio. In someembodiments, the second region has an aspect ratio. In some embodiments,both the first region and the second region have an aspect ratio. Insome embodiments, the aspect ratio is greater than 1. In someembodiments, the aspect ratio comprises a diameter-width aspect ratio.In other embodiments the aspect ratio comprises a cube-volume aspectratio.

Composite Components

Diffusion and subsequent and/or concurrent polymerization results in ahigher concentration of the more reactive monomer component in thereactive first region and a higher concentration of the less reactivemonomer components in the unreactive second region. The monomercomponents in the unreactive region may later be polymerized. In someembodiments, photopolymerization is used and the regions are generatedby patterning the light. In certain embodiments, a mask is used topattern the light. In some embodiments, a reactive region ischaracterized by exposure to light, while an unreactive region ischaracterized by a decreased or minimized exposure to light.

Polymer composites may have enhanced physical properties when comparedwith homopolymers of similar monomer species. For example, a compositewith a first polymer having high strength (e.g., storage modulus) and asecond polymer having high flexibility can result in a composite withhigher toughness than a homopolymer of either monomer species.

In some embodiments, the polymer is a molecule composed of repeatingstructural units connected by covalent chemical bonds characterized by asubstantial number of repeating units. In some embodiments, a polymercomprises equal to or greater than 10 repeating units. In certainembodiments, a polymer comprises equal to or greater than 50 repeatingunits. In some embodiments, a polymer comprises equal to or greater than100 repeating units. In some embodiments, a polymer has a high molecularweight (e.g., greater than or equal to 10,000 Da). Polymers are commonlythe polymerization product of one or more monomer precursors. In certainembodiments, a polymer is a homopolymer, wherein the polymer backboneconsists of a single repeating monomer subunit. In some embodiments, apolymer is a copolymer, wherein the polymer comprises two or moredifferent types of monomers linked in the same polymer. Copolymers maycomprise two or more monomer subunits, and include random, block,alternating, segmented, grafted, tapered, and other copolymers.

In some embodiments, a plurality of monomeric units form an oligomer,and the oligomer is composed of repeating structural units connected bycovalent chemical bonds which can be characterized by a number ofrepeating units less than that of a polymer (e.g., equal to or less than10 repeating units) and/or a lower molecular weights (e.g., less than orequal to 10,000 Da) than polymers. In some embodiments, oligomers arethe polymerization product of one or more monomer precursors.

In certain embodiments, a polymer is formed via a polymerizationreaction of polymer precursors. In some embodiments, a resin is aviscous substance comprising polymer precursors. In some embodiments, aresin can comprise a plurality of monomer components, which can beselectively activated to form polymers (e.g., they are polymerizablecomponents). The monomer components within the resin may undergopolymerization to form a polymer. In some embodiments, a resin comprisesmore than one type of monomer component. In preferred embodiments, aresin comprises a first monomer component that is more reactive than asecond monomer component. In some embodiments, a resin comprises a thirdmonomer component that can undergo polymerization.

In some embodiments, a resin is a light polymerizable liquidcomposition. The resin can comprise a first polymerizable component, asecond polymerizable component, and a photoinitiator. In someembodiments the resin has a liquid ratio of the first polymerizablecomponent to the second polymerizable component. In some embodiments,the liquid ratio is the same throughout the resin (e.g., a homogenousresin). In certain embodiments, the liquid ratio has localizedcharacteristics, wherein the ratio depends on the location in the resinthat the ratio is determined. As a non-limiting example, differences indensity and/or immiscibility may cause separation of polymerizablecomponents into sections, wherein one localized point of the resin cancomprise a liquid ratio that is different from the liquid ratio of adifferent localized point within the resin. In some embodiments theresin is exposed to a region of light (a first exposure region), whichcan initiate polymerization and generate a first polymer region. Thefirst polymer region has a first ratio of the first polymerizablecomponent to the second polymerizable component. The light exposure inthe first exposure region can activate the polymerization of a firstpolymer. In some embodiments, the first polymerizable component candiffuse freely through the resin, the second polymerizable component candiffuse freely through the resin, both the first and the secondpolymerizable components can diffuse freely through the resin, the firstpolymerizable component can diffuse freely through the first polymer,the second polymerizable component can diffuse freely through the firstpolymer, or both the first and the second polymerizable components candiffuse freely through the first polymer.

In some embodiments, the polymerizable components can diffuse throughthe resin during the polymerization of the first polymer region, thusincreasing or decreasing the amount of polymerizable component in theregion. As a non-limiting example, the light activated polymerization ofthe first polymerizable component into the first polymer in the firstpolymer region, combined with diffusion of the components, can result inthe migration of first polymerizable components into the first polymerregion, thus increasing the first ratio of the first polymerizablecomponent to the second polymerizable component within the first polymerregion, while decreasing the ratio of the first polymerizable componentto the second polymerizable component in a second region (the secondratio). In some embodiments, the second region is adjacent to,contacting, or overlapping with the first exposure region, and thesecond region is different from the first region. In certainembodiments, the resin ratio (the liquid ratio), the first region ratio,and the second region ratio of the first polymerizable component to thesecond polymerizable component are different.

As a non-limiting example, a resin comprising a ratio of the firstpolymerizable component to the second polymerizable component of 1:1 canundergo photoinitiated polymerization in a first exposure region. Afirst polymer is formed from the first polymerizable material, anddiffusion results in an increased amount of the first polymerizablematerial within the first exposure region. Following the photoinitiatedpolymerization, the first region has a first polymerizable component tosecond polymerizable component ratio (the first ratio) of 2:1. A secondregion that was not exposed to light has a first polymerizable componentto second polymerizable component ratio (the second ratio) of 1:2.Accordingly, the first ratio (2:1) is greater than the resin ratio(1:1), and the resin ratio is greater than the second ratio (1:2).

In some embodiments, the resin ratio is greater than either the firstratio or the second ratio. As a non-limiting example, a resin comprisinga ratio of the first polymerizable component to the second polymerizablecomponent of 1:1 can undergo photoinitiated polymerization in a firstexposure region. A first polymer is formed using a third polymerizablecomponent, which causes diffusion of the first polymerizable componentout of the first region. The first region has a first polymerizablecomponent to second polymerizable component ratio of 1:2. A secondexposure of light to a second region can activate polymerization of thesecond polymerizable component into a second polymer, and can causediffusion of the first polymerizable component out of the second polymerregion. The second polymer region has a first polymerizable component tosecond polymerizable component ratio of 1:3. The first polymerizablecomponent can optionally diffuse into a third polymer region, having anincreased ratio of the first polymer component to the second polymercomponent. Accordingly, the resin ratio (1:1) is greater than the firstratio (1:2), and the first ratio is greater than the second ratio (1:3).

In some embodiments the resin has a ratio of the first polymerizablecomponent to the second polymerizable component of from 1:1 to1:100,000, from 1:1 to 1:10,000, from 1:1 to 1:5,000, from 1:1 to1:2,500, from 1:1 to 1:1,000, from 1:1 to 1:500, from 1:1 to 1:100, from1:1 to 1:50, from 1:1 to 1:30, from 1:1 to 1:20, from 1:1.5 to 1:10,000,from 1:1.5 to 1:5,000, from 1:1.5 to 1:2,500, from 1:1.5 to 1:1,000,from 1:1.5 to 1:500, from 1:1.5 to 1:100, from 1:1.5 to 1:50, from 1:1.5to 1:30, from 1:1.5 to 1:20, from 1:5 to 1:10,000, from 1:5 to 1:5,000,from 1:5 to 1:2,500, from 1:5 to 1:1,000, from 1:5 to 1:500, from 1:5 to1:100, from 1:5 to 1:50, from 1:5 to 1:30, from 1:5 to 1:20, from 1:10to 1:10,000, from 1:10 to 1:5,000, from 1:10 to 1:2,500, from 1:10 to1:1,000, from 1:10 to 1:500, from 1:10 to 1:100, from 1:10 to 1:50, from1:10 to 1:30, from 1:10 to 1:20, from 100,000:1 to 1:1, from 10,000:1 to1:1, from 5,000:1 to 1:1, from 2,500:1 to 1:1, from 1,000:1 to 1:1, from500:1 to 1:1, from 100:1 to 1:1. From 50: to 1:1, from 40:1 to 1:1, from30:1 to 1:1, from 20:1 to 1:1, from 10:1 to 1:1, from 5:1 to 1:1, from100,000:1 to 1:100,000, from 10,000:1 to 1:10,000, from 5,000:1 to1:5,000, from 1,000:1 to 1:1,000, from 500:1 to 1:500, from 100:1 to1:100, from 50:1 to 1:50, from 40:1 to 1:40, from 30:1 to 1:30, from20:1 to 1:20, from 10:1 to 1:10, from 9:1 to 1:9, from 8:1 to 1:8, from7:1 to 1:7, from 6:1 to 1:6, from 5:1 to 1:5, from 4:1 to 1:4, from 3:1to 1:3, from 2:1 to 1:2, or from 1.5:1 to 1:1.5. In some embodiments,the resin has a ratio of the first polymerizable component to the secondpolymerizable component greater than 100,000:1. In some embodiments, theresin has a ratio of the first polymerizable component to the secondpolymerizable component less than 1:100,000.

In some embodiments the first region has a first ratio of the firstpolymerizable component to the second polymerizable component of from1:1 to 1:100,000, from 1:1 to 1:10,000, from 1:1 to 1:5,000, from 1:1 to1:2,500, from 1:1 to 1:1,000, from 1:1 to 1:500, from 1:1 to 1:100, from1:1 to 1:50, from 1:1 to 1:30, from 1:1 to 1:20, from 1:1.5 to 1:10,000,from 1:1.5 to 1:5,000, from 1:1.5 to 1:2,500, from 1:1.5 to 1:1,000,from 1:1.5 to 1:500, from 1:1.5 to 1:100, from 1:1.5 to 1:50, from 1:1.5to 1:30, from 1:1.5 to 1:20, from 1:5 to 1:10,000, from 1:5 to 1:5,000,from 1:5 to 1:2,500, from 1:5 to 1:1,000, from 1:5 to 1:500, from 1:5 to1:100, from 1:5 to 1:50, from 1:5 to 1:30, from 1:5 to 1:20, from 1:10to 1:10,000, from 1:10 to 1:5,000, from 1:10 to 1:2,500, from 1:10 to1:1,000, from 1:10 to 1:500, from 1:10 to 1:100, from 1:10 to 1:50, from1:10 to 1:30, from 1:10 to 1:20, from 100,000:1 to 1:1, from 10,000:1 to1:1, from 5,000:1 to 1:1, from 2,500:1 to 1:1, from 1,000:1 to 1:1, from500:1 to 1:1, from 100:1 to 1:1. From 50: to 1:1, from 40:1 to 1:1, from30:1 to 1:1, from 20:1 to 1:1, from 10:1 to 1:1, from 5:1 to 1:1, from100,000:1 to 1:100,000, from 10,000:1 to 1:10,000, from 5,000:1 to1:5,000, from 1,000:1 to 1:1,000, from 500:1 to 1:500, from 100:1 to1:100, from 50:1 to 1:50, from 40:1 to 1:40, from 30:1 to 1:30, from20:1 to 1:20, from 10:1 to 1:10, from 9:1 to 1:9, from 8:1 to 1:8, from7:1 to 1:7, from 6:1 to 1:6, from 5:1 to 1:5, from 4:1 to 1:4, from 3:1to 1:3, from 2:1 to 1:2, or from 1.5:1 to 1:1.5. In some embodiments,the first ratio is greater than 100,000:1. In some embodiments, thefirst ratio is less than 1:100,000.

In some embodiments the second region has a second ratio of the firstpolymerizable component to the second polymerizable component of from1:1 to 1:100,000, from 1:1 to 1:10,000, from 1:1 to 1:5,000, from 1:1 to1:2,500, from 1:1 to 1:1,000, from 1:1 to 1:500, from 1:1 to 1:100, from1:1 to 1:50, from 1:1 to 1:30, from 1:1 to 1:20, from 1:1.5 to 1:10,000,from 1:1.5 to 1:5,000, from 1:1.5 to 1:2,500, from 1:1.5 to 1:1,000,from 1:1.5 to 1:500, from 1:1.5 to 1:100, from 1:1.5 to 1:50, from 1:1.5to 1:30, from 1:1.5 to 1:20, from 1:5 to 1:10,000, from 1:5 to 1:5,000,from 1:5 to 1:2,500, from 1:5 to 1:1,000, from 1:5 to 1:500, from 1:5 to1:100, from 1:5 to 1:50, from 1:5 to 1:30, from 1:5 to 1:20, from 1:10to 1:10,000, from 1:10 to 1:5,000, from 1:10 to 1:2,500, from 1:10 to1:1,000, from 1:10 to 1:500, from 1:10 to 1:100, from 1:10 to 1:50, from1:10 to 1:30, from 1:10 to 1:20, from 100,000:1 to 1:1, from 10,000:1 to1:1, from 5,000:1 to 1:1, from 2,500:1 to 1:1, from 1,000:1 to 1:1, from500:1 to 1:1, from 100:1 to 1:1. From 50: to 1:1, from 40:1 to 1:1, from30:1 to 1:1, from 20:1 to 1:1, from 10:1 to 1:1, from 5:1 to 1:1, from100,000:1 to 1:100,000, from 10,000:1 to 1:10,000, from 5,000:1 to1:5,000, from 1,000:1 to 1:1,000, from 500:1 to 1:500, from 100:1 to1:100, from 50:1 to 1:50, from 40:1 to 1:40, from 30:1 to 1:30, from20:1 to 1:20, from 10:1 to 1:10, from 9:1 to 1:9, from 8:1 to 1:8, from7:1 to 1:7, from 6:1 to 1:6, from 5:1 to 1:5, from 4:1 to 1:4, from 3:1to 1:3, from 2:1 to 1:2, or from 1.5:1 to 1:1.5. In some embodiments,the second ratio is greater than 100,000:1. In some embodiments, thesecond ratio is less than 1:100,000.

In some embodiments, the first ratio is greater than the resin ratio,and the resin ratio is greater than the second ratio. In someembodiments, the first ratio is greater than the second ratio, and thesecond ratio is greater than the resin ratio. In certain embodiments,the second ratio is greater than the resin ratio, and the liquid ratiois greater than the first ratio. In some embodiments, the second ratiois greater than the first ratio, and the first ratio is greater than theresin ratio. In some embodiments, the resin ratio is greater than thefirst ratio, and the first ratio is greater than the second ratio. Incertain embodiments, the resin ratio is greater than the second ratio,and the second ratio is greater than the first ratio.

In some embodiments, a polymerizable component is a monomer, a polymer,and/or an oligomer, which are capable of entering into polymerizationthrough reactive groups. In some embodiments, a polymerizable componentis a component of a solution or molecules in a solution that are capableof polymerizing, either with itself or with other components ormolecules within the solution. In some embodiments, a first monomer, ormonomer 1, is the first monomer (polymerizable component) of a X,Y,Zvolume that is preferentially polymerized upon initial exposure to asource of radiation. In some embodiments, a second monomer, or monomer2, is a monomer (polymerizable component) that is not preferentiallypolymerized upon initial exposure to a source of radiation. In someembodiments a first polymer, or polymer 1, comprises a majority ofmonomer 1. In some embodiments a second polymer, or polymer 2, comprisesa majority of monomer 2. In certain embodiments the first monomercomprises a first polymerizable component. In some embodiments, thesecond monomer comprises a second polymerizable component.

In some embodiments, oligomers and polymer mixtures can be characterizedand differentiated from other mixtures of oligomers and polymers bymeasurements of molecular weight and molecular weight distributions. Thefollowing definitions of molecular weight can be applied for suchcharacterization (see: L. H. Sperling, Introduction to Physical PolymerScience, 2^(nd) Ed., Wiley New York (1992).). The average MolecularWeight (M) is the Average Number of Repeating Units n (or dp.)×themolecular weight or molar mass (Mi) of the repeating unit. Thenumber-average molecular weight (M_(n)) is the arithmetic mean,representing the total weight of the molecules present divided by thetotal number of molecules. Molecular weight may also be measured by theweight-average molecular weight (Mw) and the z-average molecular weightMz.

In certain embodiments, this disclosure provides methods for thegeneration of composite polymer compositions utilizing a single resin.In some embodiments, the single resin comprises a single type of monomercomponent, two types of monomer components, three types of monomercomponents, four types of monomer components, five types of monomercomponents, six types of monomer components, seven types of monomercomponents, eight types of monomer components, nine types of monomercomponents, ten types of monomer components, eleven types of monomercomponents, twelve types of monomer components, or more than twelvetypes of monomer components. In certain embodiments, the resin comprises2 polymerizable components, 3 polymerizable components, 4 polymerizablecomponents, 5 polymerizable components, 6 polymerizable components, 7polymerizable components, 8 polymerizable components, 9 polymerizablecomponents, 10 polymerizable components, 11 polymerizable components, 12polymerizable components, 13 polymerizable components, 14 polymerizablecomponents, 15 polymerizable components, or greater than 15polymerizable components,

The monomer components may be polymerized to form a polymer. In someembodiments, the monomer components react only with their own type toform a homopolymer. In some embodiments, the monomer components reactwith other types of monomer components in order to form a copolymer.

In some embodiments, the single resin comprises two monomer components,wherein one monomer component is more reactive than the other. In someembodiments, the first monomer component is at least 1.1-fold morereactive, at least 2-fold more reactive, at least 3-fold more reactive,at least 5-fold more reactive, at least 10-fold more reactive, at least15-fold more reactive, at least 25-fold more reactive, at least 50-foldmore reactive, at least 100-fold more reactive, at least 250-fold morereactive, at least 500-fold more reactive, at least 750-fold morereactive, at least 1000-fold more reactive, at least 1250-fold morereactive, at least 1500-fold more reactive, at least 2000-fold morereactive, at least 5000-fold more reactive, at least 10000-fold morereactive, at least 20000-fold more reactive, at least 50000-fold morereactive, or at least 100000-fold more reactive, than the second monomercomponent. In some embodiments, the first monomer component isinfinitely more reactive than the second monomer component.

In some embodiments, the solution comprising a first monomer componentand a second monomer component undergoes polymerization to form apolymer. In some embodiments, the first monomer component is integratedinto a first polymer. In some embodiments, the second monomer componentis integrated into a second polymer. In certain embodiments, apolymerization activator initiates the polymerization. In someembodiments, the polymerization activator comprises a radical initiator,a photoinitiator, a thermal initiator, a catalyst, a reactive species,or any combination thereof.

In certain embodiments, the radical initiator is selected from ahalogen, a chlorine, an azo compound, azobisisobutyronitrile (AIBN),1,1′-azobis(cyclohexanecarbonitrile) (ABCN), an organic peroxide,di-tert-butyl peroxide, benzoyl peroxide, methyl ethyl ketone peroxide,acetone peroxide, an inorganic peroxide, a peroxydisulfate salt, atransition metal catalyst, or any combination thereof.

Photoinitiators in this disclosure include those that can be activatedwith light and initiate polymerization of the polymerizable componentsof the resin. In some embodiments, the photoinitiator is a radicalphotoinitiator, a cationic initiator, and/or an anionic photoinitiator.In some embodiments, the photoinitiator is a Type I photoinitiator,which undergoes unimolecular bond cleavage to generate free radicals. Inother embodiments the photoinitiator is a Type II photoinitiator whichundergoes a bimolecular reaction to generate free radicals. Common TypeI photoinitiators include, but are not limited to benzoin ethers, benzilketals, α-dialkoxy-acetophenones, α-hydroxy-alkyl phenones andacyl-phosphine oxides. Common Type II photoinitiators includebenzophenones/amines and thioxanthones/amines. Cationic initiatorsinclude aryldiazonium, diaryliodonium, and triarylsulfonium salts.

In some embodiments the photoinitiator comprises an acetophenone,2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone,4′-tert-butyl-2′,6′-dimethylacetophenone, 2,2-diethyoxyacetophenone,2,2-dimethoxy-2-phenylacetophenone, 4′-ethoxyacetophenone,3′-hydroxyacetophenone, 4′-hydroxyacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone,2-hydroxy-2-methylpropiophenone,2-methyl-4′-(methylthio)-2-morpholinopropiophenone,4′-phenoxyacetophenone, a benzyl, a benzoin, benzoin ethyl ether,benzoin methyl ether, benzoin methyl ether, 4,4′-dimethoxybenzoin,4,4′-dimethylbenzil, a benzophenone,benzophenone-3,3′,4,4′-tetracarboxylic dianhydride, 4-benzobiphenyl,4,4′-bis(diethylamino)benzophenone,4,4′-bis[2-(1-propenyl)phenoxy]benzophenone,4-(diethylamino)benzophenone, 4,4′-dihydroxybenzophenone,4-(dimethylamino)benzophenone, 3,4-dimethylbenzophenone,3-hydroxybenzophenone, 3-hydroxybenzophenone, 4-hydroxybenzophenone,2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, methylbenzoylformate, Michler's ketone, a cationic initiator, an anionicinitiator, bis(4-tert-butylphenyl)iodonium perfluoro-1-butanesulfonate,bis(4-tert-butylphenyl)iodonium p-toluenesulfonate,bis(4-tert-butylphenyl)iodonium triflate,boc-methoxyphenyldiphenylsulfonium triflate,(4-tert-butylphenyl)diphenylsulfonium triflate, diphenyliodoniumhexafluorophosphate, diphenyliodonium nitrate, diphenyliodoniump-toluenesulfonate, diphenyliodonium triflate,(4-fluorophenyl)diphenylsulfonium triflate, N-hydroxynaphthalimidetriflate, N-hydroxy-5-norbornene-2,3-dicarboximideperfluoro-1-butanesulfonate, (4-iodophenyl)diphenylsulfonium triflate,(4-methoxyphenyl)diphenylsulfonium triflate,2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,(4-methylthiophenyl)methyl phenyl sulfonium triflate, 1-naphthyldiphenylsulfonium triflate, (4-phenoxyphenyl)diphenylsulfonium triflate,(4-phenylthiophenyl)diphenylsulfonium triflate, triarylsulfoniumhexafluoroantimonate salt, triarylsulfonium hexafluorophosphate salt,triphenylsulfonium perfluoro-1-butanesulfonate,triphenylsulfoniumtriflate, tris(4-tetra-butylphenyl)sulfoniumperfluoro-1-butanesulfonate, tris(4-tert-butylphenyl)sulfonium triflate,anthraquinone-2-sulfonic acid sodium salt, 2-tert-butylanthraquinone,camphorquinone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, lithiumphenyl-2,4,6-trimethylbenzoylphosphinate, 9,10-phenanthrenequinone,phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, a thioxanthone,1-chloro-4-propoxy-9H-thioxanthen-9-one, 2-chlorothioxanthen-9-one,2,4-diethyl-9H-thioxanthen-9-one, isopropyl-9H-thioxanthen-9-one,10-methylphenothiazine, thioxanthen-9-one, an Irgacure, TPO-L, aderivative thereof, or a combination thereof.

In some embodiments, the polymerization is initiated using an azocompound, 2,2′azobis(2-methylpropionitrile), 4,4′-azobis(4-cyanovalericacid), 1,1′-azobis(cyclohexanecarbonitrile), azobisisobutyronitrile,benzophenone, an inorganic peroxide, ammonium persulfate,hydroxymethanesulfinic acid monosodium salt, potassium persulfate,sodium persulfate, an organic peroxide, tert-butyl hydroperoxide,tert-butyl peracetate, cumene hydroxyperoxide,2,5-di(tert-butyl)peroxy-2,5-dimethyl-3-hexyne, dicumyl peroxide,2,5-bis(tert-butylperoxy)-2,5-dimethylhexane,2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, 2,4-pentanedione peroxide,1,1-bis(tert-butylperoxide)-3,3,5-trimethylcyclohexane,1,1-bis(tert-butylperoxy)cyclohexane, benzoyl peroxide, tert-butylperoxide, tert-butyl peroxybenzoate, TBEC, tert-butyl hydroperoxide, aderivative thereof, or a combination thereof.

In some embodiments, a thermal cure temperature is used duringpolymerization. In certain embodiments, the thermal cure temperature canbe from −50° C. to 500° C., from −10° C. to 300° C., from −5° C. to 200°C., from 0° C. to 100° C., from 10° C. to 90° C., or from 20° C. to 80°C. In certain embodiments the amount of time a material spends at athermal cure temperature is controlled. In some embodiments the amountof time the material spends at the thermal cure temperature is between 1minute and 2 weeks, between 1 minute and 1 week, between 1 minute and 6days, between 1 minute and 5 days, between 1 minute and 4 days, between1 minute and 3 days, between 1 minute and 2 days, between 1 minute and24 hours, between 1 minute and 12 hours, between 1 minute and 6 hours,between 1 minute and 3 hours, between 1 minute and 2 hours, between 1minute and 1 hour, between 5 minutes and 1 hour, between 10 minutes and1 hour, between 15 minutes and 2 hours, or between 30 minutes and 2hours.

In some embodiments, polymerization is activated using a source ofradiation. In certain embodiments, the source of radiation comprisesultraviolet light, visible light, infrared light, microwave irradiation,laser exposure, holography, DLP projection, optical lithography, pulsedlight, or a combination thereof.

In some embodiments, it is preferential that an initial intensity ofexposure is low in order to favorably induce polymerization of onemonomer component. In some embodiments, a first exposure is used to forma first polymer. In certain embodiments, the intensity of the firstexposure is between 10 nW and 100 mW, between 50 nW and 80 mW, between100 nW and 50 mW, between 100 nW and 10 mW, between 0.1 mW and 8 mW,between 0.1 mW and 6 mW, between 0.1 mW and 4 mW, or between 0.1 mW and2 mW.

In some embodiments, it is preferential that a second exposure has highintensity of exposure in order to induce polymerization of remainingmonomers that did not undergo polymerization in the first exposure. Insome embodiments, a second exposure is used to form a second polymer. Incertain embodiments, the intensity of the second exposure is between 1mW and 1000 mW, between 5 mW and 500 mW, between 5 mW and 100 mW, orbetween 10 mW and 100 mW.

In certain embodiments, the polymerization reaction comprisesstep-growth polymerization, chain-growth polymerization, radicalpolymerization, living polymerization, cationic addition polymerization,anionic addition polymerization, emulsion polymerization, solutionpolymerization, precipitation polymerization, photopolymerization, orany combination thereof. In preferred embodiments, the polymerizationreaction comprises photopolymerization.

Diffusion of all the components results in a higher concentration of themore reactive monomer component in the reacting region (e.g., a firstregion) and a higher concentration of the less reactive monomercomponents in the unreactive region (e.g., a second region). In someembodiments, the reactive region (the first region) is characterized bybeing exposed to a source of radiation during an initial exposure. Incertain embodiments, the unreactive region (the second region) is notexposed to the source of radiation during an initial exposure.

In certain embodiments, diffusion of resin components takes place. Insome embodiments, the first monomer component and the second monomercomponent diffuse through the first polymer during the polymerization ofthe first polymer. In some embodiments, as the first monomer componentsare polymerized into the first polymer, diffusion of the first monomercomponent slows. In certain embodiments, only the second monomercomponent undergoes diffusion through the first polymer. In someembodiments, the diffusion creates regions having higher concentrationof components. For example, a region-specific polymerization reactionthat polymerizes a first monomer component but not a second monomercomponent would produce the first polymer in the specific regions, whilethe second monomer component diffused toward other regions. Accordingly,a region of the composite material may comprise greater than 0.1% of afirst monomer component, greater than 5% of a first monomer component,greater than 10% of a first monomer component, greater than 20% of afirst monomer component, greater than 30% of a first monomer component,greater than 40% of a first monomer component, greater than 50% of afirst monomer component, greater than 60% of a first monomer component,greater than 70% of a first monomer component, greater than 80% of afirst monomer component, greater than 90% of a first monomer component,or greater than 95% of a first monomer component by weight. The firstmonomer component may partially or fully undergo polymerization, andtherefore a region of the composite material may comprise greater than50% of a first polymer, greater than 60% of a first polymer, greaterthan 70% of a first polymer, greater than 80% of a first polymer,greater than 90% of a first polymer, or greater than 95% of a firstpolymer by weight.

The diffusion of a second monomer component out of the first region canresult in a lowering of the amount of the second monomer component inthe first region. In some embodiments, a region of the compositematerial may comprise less than 100% of a second monomer component, lessthan 95% of a second monomer component, less than 90% of a secondmonomer component, less than 80% of a second monomer component, lessthan 70% of a second monomer component, less than 60% of a secondmonomer component, less than 50% of a second monomer component, lessthan 40% of a second monomer component, less than 30% of a secondmonomer component, less than 20% of a second monomer component, lessthan 10% of a second monomer component, or less than 5% of a secondmonomer component by weight. The unreactive region may be laterpolymerized. The second monomer component may partially or fully undergopolymerization, and therefore a region of the composite material maycomprise less than 50% of a second polymer, less than 40% of a secondpolymer, less than 30% of a second polymer, less than 20% of a secondpolymer, less than 10% of a second polymer, or less than 5% of a secondpolymer by weight.

In some embodiments, a composite material can undergo copolymerizationin selective regions. In certain embodiments, a composite materialundergoes copolymerization based on exposure to a source of radiation.In certain embodiments, diffusion of resin components takes placewherein the first monomer component and the second monomer componentdiffuse through the resin during the polymerization to form a copolymercomprising the first monomer component and the second monomer component.Accordingly, selective polymerization can provide regions comprising acopolymer, while regions that are not exposed to the source of radiationcomprise less to no copolymer. In some embodiments, the diffusioncreates regions having higher concentration of components or copolymer.For example, a region-specific polymerization reaction that polymerizesa first monomer component and a second monomer component would producethe copolymer in the specific regions, while other resin componentsdiffused toward other regions. The first monomer component and thesecond monomer component may partially or fully undergo polymerization,and therefore a region of the composite material may comprise greaterthan 50% of a first copolymer, greater than 60% of a first copolymer,greater than 70% of a first copolymer, greater than 80% of a firstcopolymer, greater than 90% of a first copolymer, or greater than 95% ofa first copolymer by weight.

In some embodiments, the irradiation of a region of the resin provides achange in the percentage of monomer presence, or a corresponding changein the presence of its corresponding polymer. In certain embodiments,this enrichment of monomer components or polymer uses a source ofradiation. In some embodiments, a higher percentage of one monomercomponent is present in a region than what would be expected by bulkcure conditions. In preferred embodiments, the percentage change isgreater than 10% (mole percentage) from initial resin values. In someembodiments, the percentage change is about 5% or greater than 5% frominitial resin values. In certain embodiments, the percent change isgreater than 20%, greater than 30%, greater than 40%, greater than 50%,greater than 60%, greater than 70%, greater than 80%, greater than 90%,greater than 95%, or greater than 98% (mole percentage) from initialresin values. As a non-limiting example, a resin comprising an initialamount of 60% Monomer A and 40% Monomer B is polymerized to provide abulk copolymerized material having an average of a 60% Monomer A and 40%Monomer B in the bulk cured copolymer. In comparison, using the methodsdisclosed herein, a region-specific preferential polymerization of thesame resin may produce a copolymer having an average composition of 50%Monomer A and 50% Monomer B, which would be a 17% decrease in theconcentration of Monomer A in the region, while monomer B wouldexperience a 25% increase in average regional copolymer composition. Thepercentage can be based on an initial and final molar percentage formonomer concentration in the starting monomer mix and for the monomerconcentration incorporated into a copolymer for a defined region ofspace. In some embodiments, the concentration or composition of startingmonomer mixtures and final polymer composition are described by weightpercentages.

In some embodiments, the composite material comprises a first monomercomponent and a second monomer component, wherein the two monomercomponents have different reactivity. The reactivity is a determinedvalue. A monomer's reactivity ratio is a value that compares themonomer's reactivity with a second monomer. Reactivity ratios of monomercomponents are available in the art (see, e.g., G. Odian, Principles ofPolymerization, 4^(th) Ed., 2004, which is incorporated herein byreference). In some embodiments, a reactivity ratio or ratio ofreactivity refers to the ratio of a rate coefficient for the reaction ofa monomer with itself to the rate coefficient of the monomer with thatof a different monomer. In some embodiments, reactivity ratio is definedby the formula:

$R = \frac{k_{11}}{k_{12}}$wherein k₁₁ is the rate coefficient corresponding to a reaction ofmonomer 1 (or a polymer with monomer 1 in a terminal position) withmonomer 1 and k₁₂ is the rate constant coefficient to a reaction ofmonomer 1 (or a polymer with monomer 1 in a terminal position) withmonomer 2. In certain embodiments, reactivity ratios depend ontemperature, concentration, and other physical conditions.

In certain embodiments, the reactivity ratio between the first monomercomponent and the second monomer component is greater than or equal toone. In some embodiments, the reactivity ratio between the first monomercomponent and the second monomer component is greater than or equal to10, greater than or equal to 20, greater than or equal to 30, greaterthan or equal to 50, greater than or equal to 100, greater than or equalto 500, greater than or equal to 1000, greater than or equal to 5000,greater than or equal to 10000, greater than or equal to 50000, orgreater than or equal to 100000. In some embodiments, the reactivityratio between the first monomer component and the second monomercomponent is from 1 to 10, from 1 to 20, from 1 to 30, from 1 to 50,from 1 to 100, from 1 to 500, from 1 to 1000, from 1 to 5000, from 1 to10000, from 1 to 50000, from 1 to 100000, from 2 to 10, from 2 to 20,from 2 to 30, from 2 to 50, from 2 to 100, from 2 to 500, from 2 to1000, from 2 to 5000, from 2 to 10000, from 2 to 50000, or from 2 to100000.

In some embodiments, the first monomer component and the second monomercomponent have a ratio of reactivity, and the ratio of reactivity of thefirst monomer component to the second monomer component is greater thanor equal to 1:1, greater than or equal to 1:1.1, greater than or equalto 1:1.25, greater than or equal to 1:1.5, greater than or equal to 1:2,greater than or equal to 1:5, greater than or equal to 1:10, greaterthan or equal to 1:20, greater than or equal to 1:30, greater than orequal to 1:50, greater than or equal to 1:100, greater than or equal to1:500, greater than or equal to 1:1000, greater than or equal to 1:5000,greater than or equal to 1:10000, greater than or equal to 1:50000, orgreater than or equal to 1:100000. In certain embodiments, the firstmonomer component is from 1-fold to 10000-fold, from 1-fold to5000-fold, from 1-fold to 1000-fold, from 1-fold to 500-fold, from1-fold to 100-fold, from 1-fold to 50-fold, from 1-fold to 10-fold, from2-fold to 10000-fold, from 2-fold to 1000-fold, from 2-fold to 500-fold,from 2-fold to 100-fold, from 2-fold to 50-fold, from 2-fold to 10-fold,from 3-fold to 1000-fold, from 3-fold to 500-fold, from 3-fold to100-fold, from 3-fold to 50-fold, from 3-fold to 10-fold, from 5-fold to1000-fold, from 5-fold to 500-fold, from 5-fold to 100-fold, from 5-foldto 50-fold, from 5-fold to 10-fold, from 10-fold to 1000-fold, from10-fold to 500-fold, from 10-fold to 100-fold, from 10-fold to 50-fold,from 50-fold to 1000-fold, from 50-fold to 500-fold, from 50-fold to100-fold, or from 100-fold to 1000-fold more reactive than the secondmonomer component.

In some embodiments, a difference in reactivity comprises a differencein a polymerization rate coefficient, a difference in concentration, adifference in functionality (such as mono-functional, di-functional,tri-functional, etc.), a difference in solubility, a difference indiffusivity of the first monomer component, a difference in diffusivityof the second monomer component, or any combination thereof. In someembodiments, techniques can be used to change the composition of thefirst polymer in comparison to the composition of the second polymer. Incertain embodiments, the composition of the first polymer is determinedby differences in reactivity between the first monomer and the secondmonomer. In specific embodiments, a difference in reactivity comprises adifference in oxygen inhibition, a difference in light absorption, adifference in photoinitator concentration, a difference in monomerconcentration, temperature, monomer solubilities, polymer solubilities,or a combination thereof.

In some embodiments, photopolymerization is used and the regions aregenerated by a mask, a photomask, or cover protecting the unreactiveregion from a light source. In certain embodiments, the mask or covercomprises a pattern, thereby forming patterned regions of polymerizationon the layer. In certain embodiments, the mask comprises a plurality oflines, a plurality of parallel lines, a plurality of brick shapes, aplurality of circular holes, a plurality of perpendicular lines forminga hatched pattern, or a combination thereof. In some embodiments, themask comprises regions that allow unimpeded radiation, wherein thesmallest axis of the region is from 20 nm to 100 microns in size, from20 nm to 10 microns in size, from 20 nm to 1 micron in size, from 20 nmto 500 nm in size, from 20 nm to 300 nm in size, from 100 nm to 100microns in size, from 100 nm to 10 microns in size, from 100 nm to 1micron in size, from 100 nm to 500 nm in size, from 200 nm to 100microns in size, from 200 nm to 50 microns in size, from 200 nm to 25microns in size, from 200 nm to 5 microns in size, from 200 nm to 1micron in size, from 1 micron to 100 microns in size, from 1 to 50microns in size, from 1 to 40 microns in size, from 1 to 30 microns insize, from 1 to 20 microns in size, from 1 to 10 microns in size, from 2to 100 microns in size, from 2 to 50 microns in size, from 2 to 25microns in size, from 2 to 10 microns in size, from 4 to 100 microns insize, from 4 to 50 microns in size, from 4 to 40 microns in size, from 4to 20 microns in size, form 4 to 10 microns in size, from 6 to 100microns in size, from 6 to 50 microns in size, from 6 to 25 microns insize, from 6 to 20 microns in size, from 10 to 100 microns in size, orfrom 10 to 50 microns in size.

In certain embodiments, photopolymers are fabricated by “vat” processesin which light is used to selectively cure a section or portion of resinin a vat or reservoir. Each layer of the object being fabricated may beselectively exposed to light in a single exposure or by scanning a beamof light across the layer. Specific techniques include stereolithography(SLA), Digital Light Processing (DLP), holographic projection, and twophoton-induced photopolymerization (TPIP).

Processes of Manufacture

Advances in three-dimensional (3D) printing and/or additivemanufacturing provide an ability to quickly and efficiently generatepolymer-based orthodontic appliances. Most 3D printing techniques relyon a layer by layer generation technique, which makes it difficult toproduce devices which have multiple materials or compounds. In certainembodiments herein, multiple layers in an orthodontic appliance can beformed that each provide different physical properties. In someembodiments herein, at least one layer provides a mechanical strength(modulus) required to apply an orthodontic force necessary to adjust apatient's tooth while at least one other layer provides elasticity sothat the composite material is not easily broken or damaged.

In some embodiments, additive manufacturing refers to a variety oftechnologies which fabricate three-dimensional objects directly fromdigital models through an additive process. In some aspects, successivelayers of material are deposited and cured in place. In someembodiments, 3D printing can be used to fabricate appliances. In certainembodiments, 3D printing can be used to fabricate orthodonticappliances. In some embodiments, 3D printing involves jetting orextruding one or more materials onto a build surface in order to formsuccessive layers of the object geometry.

The various embodiments of the orthodontic appliances presented hereincan be fabricated using a composite material in a wide variety of ways.In some embodiments, the orthodontic appliances herein (or portionsthereof) can be produced using direct fabrication, such as additivemanufacturing techniques (also referred to herein as “3D printing”).Additive manufacturing techniques can be categorized as follows: (1) vatphotopolymerization (e.g., stereolithography), in which an object isconstructed layer by layer from a vat of liquid photopolymer resin; (2)material jetting, in which material is jetted onto a build platformusing either a continuous or drop on demand (DOD) approach; (3) binderjetting, in which alternating layers of a build material (e.g., apowder-based material) and a binding material (e.g., a liquid binder)are deposited by a print head; (4) fused deposition modeling (FDM), inwhich material is drawn though a nozzle, heated, and deposited layer bylayer; (5) powder bed fusion, including but not limited to direct metallaser sintering (DMLS), electron beam melting (EBM), selective heatsintering (SHS), selective laser melting (SLM), and selective lasersintering (SLS); (6) sheet lamination, including but not limited tolaminated object manufacturing (LOM) and ultrasonic additivemanufacturing (UAM); and (7) directed energy deposition, including butnot limited to laser engineering net shaping, directed lightfabrication, direct metal deposition, and 3D laser cladding. Forexample, stereolithography can be used to directly fabricate one or moreof the appliances herein. In some embodiments, stereolithographyinvolves selective polymerization of a photosensitive resin (e.g., aphotopolymer) according to a desired cross-sectional shape using light(e.g., ultraviolet light). The object geometry can be built up in alayer-by-layer fashion by sequentially polymerizing a plurality ofobject cross-sections. As another example, the appliances herein can bedirectly fabricated using selective laser sintering. In someembodiments, selective laser sintering involves using a laser beam toselectively melt and fuse a layer of powdered material according to adesired cross-sectional shape in order to build up the object geometry.As yet another example, the appliances herein can be directly fabricatedby fused deposition modeling. In some embodiments, fused depositionmodeling involves melting and selectively depositing a thin filament ofthermoplastic polymer in a layer-by-layer manner in order to form anobject. In yet another example, material jetting can be used to directlyfabricate the appliances herein. In some embodiments, material jettinginvolves jetting or extruding one or more materials onto a build surfacein order to form successive layers of the object geometry. Any of theseadditive manufacturing methods can be used in conjunction with thepresent invention; for example, by applying light at some portion of theprocess to cure the material being deposited.

Alternatively or in combination, the appliance can be fabricated withmachining such as an appliance fabricated from a block of material withcomputer numeric control machining. The system can comprise one or moreprocessors configured with instructions to: determine a movement path tomove one or more teeth from an initial arrangement to a targetarrangement; determine an appliance geometry for an orthodonticappliance comprising a shell and an integrally formed component; andgenerate instructions for direct fabrication of the orthodonticappliance, wherein the instructions are configured to cause directfabrication of the shell using a resin comprising a first monomercomponent and direct fabrication of the integrally formed componentusing a second, different monomer component in the resin. For example,in some embodiments, instructions can be configured to cause directfabrication of both the shell and the integrally formed component usinga resin comprising both the first monomer component and the secondmonomer component. Selective application of light to one of the shell orthe integrally formed component, in accordance with techniques disclosedherein, can produce polymer compositions of the shell and integrallyformed component that differ in their respective percentages of firstand second monomer components. For example, the shell can have anincreased (or alternatively decreased) percentage of the first monomercomponent relative to the one or both of the integrally formed componentand the resin, and a decreased (or alternatively increased) percentageof the second monomer component relative to the one or both of theintegrally formed component and the resin.

In some embodiments, continuous direct fabrication methods forphotopolymers are used herein. For example, a direct fabrication processcan achieve continuous build-up of an object geometry by continuousmovement of the build platform (e.g., along the vertical or Z-direction)during the irradiation phase, such that the hardening depth of theirradiated photopolymer is controlled by the movement speed.Accordingly, continuous polymerization of material on the build surfacecan be achieved.

In some embodiments, a continuous direct fabrication method utilizes aheliolithography approach in which the liquid photopolymer is cured withfocused radiation while the build platform is continuously rotated andraised. Accordingly, the object geometry can be continuously built upalong a spiral build path. Such methods are described in U.S. PatentPublication No. 2014/0265034, the disclosure of which is incorporatedherein by reference in its entirety.

In certain embodiments, continuous liquid interface production of 3Dobjects is used herein. Such methods have been reported in J. Tumblestonet al. (Science, 2015, 347 (6228), pp 1349-1352), which is herebyincorporated by reference in its entirety for description of theprocess. In some embodiments, continuous direct fabrication methodsinvolve extruding a composite material composed of a curable liquidmaterial surrounding a solid strand. The composite material can beextruded along a continuous three-dimensional path in order to form theobject. Such methods are described in U.S. Patent Publication No.2014/0061974, the disclosure of which is incorporated herein byreference in its entirety.

In some embodiments, the direct fabrication methods provided hereinbuild up the composite material geometry in a layer-by-layer fashion,with successive layers being formed in discrete build steps.Alternatively or in combination, direct fabrication methods that allowfor continuous build-up of composite material geometry can be used,referred to herein as “continuous direct fabrication.” Various types ofcontinuous direct fabrication methods can be used. As an example, insome embodiments, the appliances herein are fabricated using “continuousliquid interphase printing,” in which an object is continuously built upfrom a reservoir of photopolymerizable resin by forming a gradient ofpartially cured resin between the building surface of the object and apolymerization-inhibited “dead zone.” In some embodiments, asemi-permeable membrane is used to control transport of aphotopolymerization inhibitor (e.g., oxygen) into the dead zone in orderto form the polymerization gradient. Continuous liquid interphaseprinting can achieve fabrication speeds about 25 times to about 100times faster than other direct fabrication methods, and speeds about1000 times faster can be achieved with the incorporation of coolingsystems. Continuous liquid interphase printing is described in U.S.Patent Publication Nos. 2015/0097315, 2015/0097316, and 2015/0102532,the disclosures of each of which are incorporated herein by reference intheir entirety.

In another example, a continuous direct fabrication method can involveextruding a composite material composed of a curable liquid materialsurrounding a solid strand. The composite material can be extruded alonga continuous three-dimensional path in order to form the object. Suchmethods are described in U.S. Patent Publication No. 2014/0061974, thedisclosure of which is incorporated herein by reference in its entirety.Patterned light can be applied during the fabrication process as a wayto create a composite material as part of the extruded material, forexample.

The direct fabrication approaches provided herein are compatible with awide variety of materials, including but not limited to one or more ofthe following: a polyester, a co-polyester, a polycarbonate, athermoplastic polyurethane, a polypropylene, a polyethylene, apolypropylene and polyethylene copolymer, an acrylic, a cyclic blockcopolymer, a polyetheretherketone, a polyamide, a polyethyleneterephthalate, a polybutylene terephthalate, a polyetherimide, apolyethersulfone, a polytrimethylene terephthalate, a styrenic blockcopolymer (SBC), a silicone rubber, an elastomeric alloy, athermoplastic elastomer (TPE), a thermoplastic vulcanizate (TPV)elastomer, a polyurethane elastomer, a block copolymer elastomer, apolyolefin blend elastomer, a thermoplastic co-polyester elastomer, athermoplastic polyamide elastomer, a thermoset material, or combinationsthereof. The materials used for direct fabrication can be provided in anuncured form (e.g., as a liquid, resin, powder, etc.) and can be cured(e.g., by photopolymerization, light curing, gas curing, laser curing,crosslinking, etc.) in order to form an appliance or a portion thereof.In certain embodiments, the appliance is an orthodontic appliance. Theproperties of the material before curing may differ from the propertiesof the material after curing. Once cured, the materials herein canexhibit sufficient strength, stiffness, durability, biocompatibility,etc. for use in an orthodontic appliance. The post-curing properties ofthe materials used can be selected according to the desired propertiesfor the corresponding portions of the appliance.

In some embodiments, relatively rigid portions of an appliance can beformed via direct fabrication using one or more of the followingmaterials: a polyester, a co-polyester, a polycarbonate, a thermoplasticpolyurethane, a polypropylene, a polyethylene, a polypropylene andpolyethylene copolymer, an acrylic, a cyclic block copolymer, apolyetheretherketone, a polyamide, a polyethylene terephthalate, apolybutylene terephthalate, a polyetherimide, a polyethersulfone, and/ora polytrimethylene terephthalate.

In some embodiments, relatively elastic portions of an appliance can beformed via direct fabrication using one or more of the followingmaterials: a styrenic block copolymer (SBC), a silicone rubber, anelastomeric alloy, a thermoplastic elastomer (TPE), a thermoplasticvulcanizate (TPV) elastomer, a polyurethane elastomer, a block copolymerelastomer, a polyolefin blend elastomer, a thermoplastic co-polyesterelastomer, and/or a thermoplastic polyamide elastomer.

Machine parameters can include curing parameters. For digital lightprocessing (DLP)-based curing systems, curing parameters can includepower, curing time, and/or grayscale of the full image. For laser-basedcuring systems, curing parameters can include power, speed, beam size,beam shape and/or power distribution of the beam. For printing systems,curing parameters can include material drop size, viscosity, and/orcuring power. These machine parameters can be monitored and adjusted ona regular basis (e.g., some parameters at every 1_(-x) layers and someparameters after each build) as part of the process control on thefabrication machine. Process control can be achieved by including asensor on the machine that measures power and other beam parametersevery layer or every few seconds and automatically adjusts them with afeedback loop. For DLP machines, gray scale can be measured andcalibrated before, during, and/or at the end of each build, and/or atpredetermined time intervals (e.g., every n^(th) build, once per hour,once per day, once per week, etc.), depending on the stability of thesystem. In addition, material properties and/or photo-characteristicscan be provided to the fabrication machine, and a machine processcontrol module can use these parameters to adjust machine parameters(e.g., power, time, gray scale, etc.) to compensate for variability inmaterial properties. By implementing process controls for thefabrication machine, reduced variability in appliance accuracy andresidual stress can be achieved.

Optionally, the direct fabrication methods described herein allow forfabrication of an appliance including multiple materials, referred toherein as “multi-material direct fabrication.” In some embodiments, amulti-material direct fabrication method involves concurrently formingan object from multiple materials in a single manufacturing step. Forinstance, a multi-tip extrusion apparatus can be used to selectivelydispense multiple types of materials from distinct material supplysources in order to fabricate an object from a plurality of differentmaterials. Such methods are described in U.S. Pat. No. 6,749,414, thedisclosure of which is incorporated by reference in its entirety.Alternatively or in combination, a multi-material direct fabricationmethod can involve forming an object from multiple materials in aplurality of sequential manufacturing steps. For instance, a firstportion of the object can be formed from a first material in accordancewith any of the direct fabrication methods herein, then a second portionof the object can be formed from a second material in accordance withmethods herein, and so on, until the entirety of the object has beenformed. In some embodiments, a multi-material direct fabrication methodcan involve forming an object from multiple monomer components in asingle resin using sequential manufacturing steps. For instance, a firstportion of an object can be formed from a first selective polymerizationof a first monomer with any of the polymerization and fabricationmethods herein, then a second portion of the object can be formed fromthe same resin in accordance with the polymerization and curing methodsdisclosed herein, and so on, until the entirety of the object has beenformed.

Direct fabrication can provide various advantages compared to othermanufacturing approaches. For instance, in contrast to indirectfabrication, direct fabrication permits production of an appliancewithout utilizing any molds or templates for shaping the appliance, thusreducing the number of manufacturing steps involved and improving theresolution and accuracy of the final appliance geometry. Additionally,direct fabrication permits precise control over the three-dimensionalgeometry of the appliance, such as the appliance thickness. Complexstructures and/or auxiliary components can be formed integrally as asingle piece with the appliance shell in a single manufacturing step,rather than being added to the shell in a separate manufacturing step.In some embodiments, direct fabrication is used to produce appliancegeometries that would be difficult to create using alternativemanufacturing techniques, such as appliances with very small or finefeatures, complex geometric shapes, undercuts, interproximal structures,shells with variable thicknesses, and/or internal structures (e.g., forimproving strength with reduced weight and material usage). For example,in some embodiments, the direct fabrication approaches herein permitfabrication of an appliance with feature sizes of less than or equal toabout 5 μm, or within a range from about 5 μm to about 50 μm, or withina range from about 20 μm to about 50 μm.

Machine parameters can include curing parameters. For digital lightprocessing (DLP)-based curing systems, curing parameters can includepower, curing time, and/or grayscale of the full image. For laser-basedcuring systems, curing parameters can include power, speed, beam size,beam shape and/or power distribution of the beam. For printing systems,curing parameters can include material drop size, viscosity, and/orcuring power. These machine parameters can be monitored and adjusted ona regular basis (e.g., some parameters at every 1_(-x) layers and someparameters after each build) as part of the process control on thefabrication machine. Process control can be achieved by including asensor on the machine that measures power and other beam parametersevery layer or every few seconds and automatically adjusts them with afeedback loop. For DLP machines, gray scale can be measured andcalibrated at the end of each build. In addition, material propertiesand/or photo-characteristics can be provided to the fabrication machine,and a machine process control module can use these parameters to adjustmachine parameters (e.g., power, time, gray scale, etc.) to compensatefor variability in material properties. By implementing process controlsfor the fabrication machine, reduced variability in appliance accuracyand residual stress can be achieved.

In many embodiments, environmental variables (e.g., temperature,humidity, Sunlight or exposure to other energy/curing source) aremaintained in a tight range to reduce variable in appliance thicknessand/or other properties. Optionally, machine parameters can be adjustedto compensate for environmental variables. Increased temperature duringthe light exposure stage can aid in the use of higher viscositymaterials than one would normally be able to use in a vat-style process.For example, temperatures greater than 50° C. can be useful. In someinstances temperatures can range from 50° C. to 100° C. In someembodiments, the vat temperature can be greater than 100° C., for resinswith sufficient stability.

In many embodiments, post-processing of appliances includes cleaning,post-curing, and/or support removal processes. Relevant post-processingparameters can include purity of cleaning agent, cleaning pressureand/or temperature, cleaning time, post-curing energy and/or time,and/or consistency of support removal process. These parameters can bemeasured and adjusted as part of a process control scheme. In addition,appliance physical properties can be varied by modifying thepost-processing parameters. Adjusting post-processing machine parameterscan provide another way to compensate for variability in materialproperties and/or machine properties.

In some embodiments, the direct fabrication approaches herein allow forproduction of an orthodontic appliance in a time interval less than orequal to about 1 hour, about 30 minutes, about 25 minutes, about 20minutes, about 15 minutes, about 10 minutes, about 5 minutes, about 4minutes, about 3 minutes, about 2 minutes, about 1 minutes, or about 30seconds. Such manufacturing speeds allow for rapid “chair-side”production of customized appliances, e.g., during a routine appointmentor checkup.

In some embodiments, an appliance includes a built-in layer or coatingintegrally formed with the appliance shell by direct fabrication. Thelayer or coating can be located on one or more of a buccal surface,lingual surface, occlusal surface, exterior surface, and/or interiorsurface of the shell. The layer or coating can be formed from one ormore materials configured to provide additional functionality to theappliance. For example, the layer or coating can be formed from amoisture resistant material, e.g., in order to act as a sealant toreduce stress relaxation of the appliance associated with waterabsorption. As another example, the layer or coating can be formed froma material that resists or reduces staining. In another example, thelayer or coating can be used to reduce friction between the appliance,the patient's teeth and/or another device. In some embodiments, aprotective layer or coating is integrally formed into the occlusalsurfaces of an appliance to protect the appliance, the patient's teeth,and/or another device, e.g., from grinding, pressure, and interference.In yet another example, the layer or coating can incorporate therapeuticagents or functional agents for drug delivery, flavoring, etc. Thedirect fabrication methods herein allow such layers or coatings to beformed with the shell in a single processing step.

Composite Materials

In some embodiments, polymer composites have enhanced physicalproperties when compared with homopolymers of similar monomer species.For example, a composite material comprising a first polymer having highstrength (e.g., high storage modulus) and a second polymer having highflexibility can form a composite with higher strength and flexibilitythan a homopolymer of either monomer species.

In some embodiments, the step of exposing the light polymerizable liquidcomposition to the first exposure results in a polymerization-inducedphase separation in the light polymerizable liquid composition along oneor more lateral directions. In some embodiments, the phase separationresults in a concentration gradient between the two polymer regions, butseparation between the two polymerizable components in the lateraldimensions still occurs. In some embodiments, the lateral dimension is alength or area characterized by the x-axis, the y-axis or both the x-and y-axes as show in FIG. 7 . In some embodiments, lateral dimensioncorresponds to the axes defined by the print area of an additivemanufacturing devices, while the vertical dimension (z-axis) refers tothe direction in which layers are added.

As a non-limiting example, a resin comprising a first monomer componentand a second monomer component that is exposed to a source of radiationcan undergo polymerization of a first polymer. The concentration of thefirst polymer can be highest at the point nearest the radiation source.Subsequent polymerization to form the second polymer will be more highlyconcentrated at a point further from the radiation source. Accordingly,a gradient exists between the first polymer and the second polymer, butseparation between the two components is present. If the light source isplaced in a lateral direction, the gradient can form in a lateraldirection as well.

In some embodiments, the step of exposing the light polymerizable liquidcomposition to the first exposure results in a polymerization-inducedphase separation in the light polymerizable liquid composition along avertical direction. In some embodiments, the phase separation results ina concentration gradient between the two polymer regions, but separationbetween the two polymerizable components in the vertical dimension stilloccurs. In some embodiments, the lateral dimension is a length or areacharacterized by the x-axis, the y-axis or both the x- and y-axes asshow in FIG. 7 . In some embodiments, lateral dimension corresponds tothe axes defined by the print area of an additive manufacturing devices,while the vertical dimension (z-axis) refers to the direction in whichlayers are added.

As a non-limiting example, a resin comprising a first monomer componentand a second monomer component that is exposed to a source of radiationcan undergo polymerization of a first polymer. The concentration of thefirst polymer can be highest at the point nearest the radiation source.Subsequent polymerization to form the second polymer will be more highlyconcentrated at a point further from the radiation source. Accordingly,a gradient exists between the first polymer and the second polymer, butseparation between the two components is present. That is, the twopolymers are different in composition and have different materialproperties. If the light source is placed in a vertical direction, thegradient can form in a vertical direction as well.

In some embodiments, the first monomer component comprises an acrylicmonomer, an acrylamide, a methacrylamide, an acrylonitrile, a bisphenolacrylic, a carbohydrate, a fluorinated acrylic, a maleimide, anacrylate, 4-acetoxyphenethyl acrylate, acryloyl chloride,4-acryloylmorpholine, 2-(acryloyloxy)ethyl]trimethylammonium chloride,2-(4-benzoyl-3-hydroxyphenoxy)ethyl acrylate, benzyl 2-propylacrylate,butyl acrylate, tert-butyl acrylate, 2[[(butylamino)carbonyl]oxy]ethylacrylate, tert-butyl 2-bromoacrylate, 2-carboxyethyl acrylate,2-chloroethyl acrylate, 2-(diethylamino)ethyl acrylate, di(ethyleneglycol) ethyl ether acrylate, 2-(dimethylamino)ethyl acrylate,3-(dimethylamino)propyl acrylate, dipentaerythriol penta-/hexa-acrylate,ethyl acrylate, 2-ethylacryloyl chloride, ethyl 2-(bromomethyl)acrylate,ethyl cis-(beta-cyano)acrylate, ethylene glycol dicyclopentenyl etheracrylate, ethylene glycol methyl ether acrylate, ethylene glycol phenylether acrylate, ethyl 2-ethylacrylate, 2-ethylexyl acrylate, ethyl2-propylacrylate, ethyl 2-(trimethylsilylmethyl)acrylate, hexylacrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate,2-hydroxy-3-phenoxypropyl acrylate, hydroxypropyl acrylate, isobornylacrylate, isobutyl acrylate, isodecyl acrylate, isooctyl acrylate,lauryl acrylate, methyl 2-acetamidoacrylate, methyl acrylate, amethylene malonate (e.g., dibutyl methylene malonate, dihexyl methylenemalonate, or dicyclohexyl methylene malonate), a methylene malonatemacromerer (e.g, a polyester of 2-methylenemalonate such as Forza B3000XP), methyl α-bromoacrylate, methyl 2-(bromomethyl)acrylate, methyl2-(chloromethyl)acrylate, methyl 3-hydroxy-2-methylenebutyrate, methyl2-(trifluoromethyl)acrylate, octadecyl acrylate, pentabromobenzylacrylate, pentabromophenyl acrylate, pentafluorophenyl acrylate,poly(ethylene glycol) diacrylate, poly(ethylene glycol) methyl etheracrylate, poly(propylene glycol) acrylate, epoxidized soybean oilacrylate, 3-sulfopropyl acrylate, tetrahydrofuryl acrylate,2-tetrahydropyranyl acrylate, 3-(trimethoxysilyl)propyl acrylate,3,5,5-trimethylhexyl acrylate, 10-undecenyl acrylate, urethane acrylate,urethane acrylate methacrylate, tricylcodecane diacrylate, isobornylacrylate, a methacrylate, allyl methacrylate, benzyl methacrylate,(2-boc-amino)ethyl methacrylate, tert-butyl methacrylate,9H-carbazole-9-ethylmethacrylate, 3-chloro-2-hydroxypropyl methacrylate,cyclohexyl methacrylate, 1,10-decamethylene glycol dimethacrylate,ethylene glycol dicyclopentenyl ether methacrylate, ethylene glycolmethyl ether methacrylate, 2-ethylhexyl methacrylate, furfurylmethacrylate, glycidyl methacrylate, glycosyloxyethyl methacrylate,hexyl methacrylate, hydroxybutyl methacrylate,2-hydroxy-5-N-methacrylamidobenzoic acid, isobutyl methacrylate,methacryloyl chloride, methyl methacrylate, mono-2-methacryloyloxy)ethylsuccinate, 2-N-morpholinoethyl methacrylate, 1-naphthyl methacrylate,pentabromophenyl methacrylate, phenyl methacrylate, pentabromophenylmethacrylate, TEMPO methacrylate, 3-sulfopropyl methacrylate,triethylene glycol methyl ether methacrylate,2-[(1′,1′,1′-trifluoro-2′-(trifluoromethyl)-2′Ohdroxy)propyl]-3-norbornylmethacrylate, 3,3,5-trimethylcyclohexyl methacrylate,(trimethylsilyl)methacrylate, vinyl methacrylate, isobornylmethacrylate, bisphenol A dimethacrylate, an Omnilane OC, tert-butylacrylate, isodecyl acrylate, tricylcodecane diacrylate, a polyfunctionalacrylate, N,N′-methylenebisacrylamide, 3-(acryloyloxy)-2-hydroxypropyl)methacrylate, bis[2-(methacryloyloxy)ethyl] phosphate, 1,3-butanedioldiacrylate, 1,4-butanediol diacrylate, diurethane dimethacrylate,N,N′-ethylenebis(acrylamide), glycerol 1,3-diglycerolate diacrylate,1,6-hexanediol diacrylate, hydroxypivalyl hydroxypivalatebis[6-(acryloyloxy)hexanoate], neopentyl glycol diacrylate,pentaerythritol diacrylate, 1,3,6-triacryloyl hexahydro-1,3,5-triazine,trimethlolpropane ethoxylate, tris[2-(acryloyloxy)ethyl] isocyanurate,any derivative thereof, or a combination thereof.

In certain embodiments, the second monomer component comprises a vinylester, vinyl acetate, vinyl benzoate, vinyl 4-tert-butylbenzoate, vinylchloroformate, vinyl cinnamate, vinyl decanoate, vinyl neodecanoate,vinyl neononanoate, vinyl pivalate, vinyl propionate, vinyl stearate,vinyl trifluoroacetate, vinyl valerate, vinyl laurate, isobutyl vinylether, Omnilane OC 1005, Omnilane OC 3005, Omnilane OC 2005, a methylenemalonate (e.g., dibutyl methylene malonate, dihexyl methylene malonate,or dicyclohexyl methylene malonate), a methylene malonate macromerer(e.g, a polyester of 2-methylenemalonate such as Forza B3000 XP), ananhydride, hexahydro-4-methylphthalic anhydride, cis-aconitic anhydride,s-acetylmercaptosuccinic anhydride, 4-amino-1,8-naphthalic anhydride,endo-bicyclo[2.2.2]oct-5-ene-2,3-dicarboxylic anhydride,3,3′4,4′-biphenyltetracarboxylic dianhydride, isatoic anhydride,5-bromoisatoic anhydride, bromomaleic anhydride, 4-bromo-1,8-naphthalicanhydride, citraconic anhydride, crotonic anhydride,1,2-cyclohexanedicarboxylic anhydride, cyclopentene dicarboxylicanhydride, 2,3-dichloromaleic anhydride, 3,6-dichlorophthalic anhydride,diethylenetriaminepentaacetic dianhydride, 3,6-difluorophthalicanhydride, diglycolic anhydride, 2,2-dimethylglutaric anhydride,3,3-dimethylglutaric anhydride, diphenic anhydride,(2-dodecen-1-yl)succinic anhydride, glutaric anhydride,hexafluoroglutaric anhydride, homophthalic anhydride, 3-hydroxyphthalicanhydride, isatoic anhydride, maleic anhydride, 3-methylglutaricanhydride, naphthalic anhydride, 3-nitrophthalic anhydride,2,5-oxazolidinedione, phenylsuccinic anhydride, phenylmaleic anhydride,2,3-pyrazinedicarboxylic anhydride, pyromellitic dianhydride, succinicanhydride, tetrabromopthalic anhydride, 3,4,5,6-tetramethyleneglutaricanhydride, trimellitic anhydride, 2-(triphenylphosphoranylidene)succinicanhydride, vinyl tert-butyl benzoate, divinyl adipate, any derivativethereof, or a combination thereof.

In some embodiments, a third monomer component is provided. In someembodiments, the third monomer component acts to bind the first monomercomponent and the second monomer component into a cohesive compositematerial. In certain embodiments, the third monomer component is anelastomer. In certain embodiments, the third monomer component comprisesan Exothane, urethane dimethacrylate, Exothane 9, Exothane 10, Exothane8, Exothane 26, Exothane 24, Exothane 32, Exothane 108, Exothane 126, amethylene malonate (e.g., dibutyl methylene malonate, dihexyl methylenemalonate, or dicyclohexyl methylene malonate), a methylene malonatemacromerer (e.g, a polyester of 2-methylenemalonate such as Forza B3000XP), urethane epoxy methacrylate, tert-butylacrylate, an epoxidemonomer, allyl glycidyl ether, bis[4-(glycidyloxy)phenyl]methane,1,3-butadiene diepoxide, 1,4-butanediol diglycidyl ether, 1,4-butanedioldiglycidyl ether, butyl glycidyl ether, tert-butyl glycidyl ether,4-chlorophenyl glycidyl ether, cyclohexene oxide, cyclopentene oxide,dicyclopentadiene dioxide, 1,2,5,6-diepoxycyclooctane,1,2,7,8-diepoxyoctane, diglycidyl 1,2-cyclohexanedicarboxylate,N,N-diglycidyl-4-glycidyloxyaniline, 1,2-epoxybutane,cis-2,3-epoxybutane, 3,4-epoxy-1-butene, 3,4-epoxycyclohexylmethyl3,4-epoxycyclohexanecarboxylate, 1,2-epopxydodecane,1,2-epoxyhexadecane, 1,2-epoxyhexane, 1,2-epoxy-5-hexene,1,2-epoxy-2-methylpropane, exo-2,3-epoxynorbornane, 1,2-epoxyoctane,1,2-epoxypentane, 1,2-epoxy-3-phenoxypropane,1,2-epoxy-3-phenoxypropane, (2,3-epoxypropyl)benzene,N-(2,3-epoxypropyl)phthalimide, exo-3,6-epoxy-1,2,3,6-tetrahydrophthalicanhydride, 3,4-epoxytetrahydrothiophene, 2-ethylhexyl glycidyl ether,furfuryl glycidyl ether, glycerol diglycidyl ether, glicidyl isopropylether, glicidyl 4-methoxyphenyl ether, isophorone oxide,4,4′-methylenebis(N,N-diglycidylaniline), 2-methyl-2-vinyloxirane,neopentyl glycol diglycidyl ether, α-pinene oxide, propylene oxide,resorcinol diglycidyl ether, cis-stillbene oxide, styrene oxide,tetraphenylolethane glycidyl ether, tris(2,3-epoxypropyl) isocyanurate,urethane epoxy methacrylate, any derivative thereof, or a combinationthereof.

In some embodiments, exposing the light polymerizable liquid to a firstexposure of light characterized by a first region generates a firstpolymer in a first polymer region. In certain embodiments, the firstpolymer region is characterized by greater than or equal to 50%incorporation of the first polymerizable component. In some embodiments,a second exposure of light characterized by a second region generates asecond polymer in a second polymer region. In preferred embodiments, thefirst polymer region and the second polymer region are different. Insome embodiments, the second polymer region is characterized by greaterthan or equal to 50% incorporation of the second polymerizablecomponent. In preferred embodiments the second region is adjacent to,contacting, or overlapping with, the first region.

In some embodiments, there are regional changes in the polymercomposition, in contrast to what the polymer composition would be underbulk cure conditions. As a non-limiting example, a region of a resin maybe irradiated with a source of radiation, wherein the resin comprisesMonomer A and Monomer B. If the two monomers are capable ofcopolymerizing, then the composition of the copolymer that is formedwould tend to average the input percentage (for example, 50% Monomer Aand 50% Monomer B). However, using the techniques of this disclosure,the polymer composition can be altered in a three-dimensional X, Y, andZ region to be enriched in one of the two monomers, or the polymers themonomers form upon polymerization. For example, a planar X, Y-dimensionwith a vertical Z-plane may comprise 60% Polymer A and 40% Polymer B ata low value of the Z-plane, while a high value of the Z-plane maycomprise 40% Polymer A and 60% Polymer B. In a second example, a resininitially comprising 60% Monomer A and 40% Monomer B may undergocontrolled irradiation, thereby forming a region comprising 70% MonomerA and 30% Monomer B. In general, this disclosure provides a way to alterthe polymer or copolymer composition in a defined X,Y region (and 3dimensional X,Y,Z-space) to have a different composition than would befound under bulk polymerization. In some embodiments, the polymercomposition in the irradiated region may comprise from 5% to 95% PolymerA and from 5% to 95% Polymer B. In certain embodiments, the polymercomposition in the irradiated region may comprise from 50% to 100%Polymer A and from 0% to 50% Polymer B. In some embodiments, the polymercomposition in the irradiated region may comprise from 1% to 100%Polymer A and from 0% to 99% Polymer B.

In some embodiments, the polymer formed in the first exposure region ischaracterized by one or more polymer properties that differ from thepolymer formed in the second region. In certain embodiments, the firstpolymer and the second polymer differ from one another in Tg (glasstransition temperature), storage modulus, elongation to break, or anycombination thereof. In certain embodiments, the first polymer ischaracterized by a Tg that is at least 5° C. greater than the secondpolymer, at least 10° C. greater than the second polymer, at least 20°C. greater than the second polymer, at least 30° C. greater than thesecond polymer, at least 50° C. greater than the second polymer, atleast 75° C. greater than the second polymer, or at least 100° C.greater than the second polymer. In some embodiments, the first polymeris characterized by a Tg that is from 1° C. to 5° C. greater than thesecond polymer, from 1° C. to 10° C. greater than the second polymer,from 1° C. to 20° C. greater than the second polymer, from 1° C. to 30°C. greater than the second polymer, from 1° C. to 50° C. greater thanthe second polymer, from 1° C. to 75° C. greater than the secondpolymer, from 1° C. to 100° C. greater than the second polymer, from 5°C. to 500° C. greater than the second polymer, from 10° C. to 1000° C.greater than the second polymer, from 20° C. to 200° C. greater than thesecond polymer, from 30° C. to 300° C. greater than the second polymer,from 50° C. to 500° C. greater than the second polymer, from 75° C. to1000° C. greater than the second polymer, or from 100° C. to 1000° C.greater than the second polymer. In alternative embodiments, any of theabove relationships can be reversed, that is, the second polymer canhave a greater Tg than the first polymer characterized by any of theranges disclosed above. More generally, each of the above ranges cancharacterize a difference between the values if Tg of the first andsecond polymer. Thus, the two polymers' glass transition temperaturescan differ by at least 5° C., at least 10° C., at least 20° C., at least30° C., at least 50° C., at least 75° C., or at least 100° C.; or theycan differ by an amount from 1° C. to 5° C., 1° C. to 10° C., 1° C. to20° C., 1° C. to 30° C., 1° C. to 50° C., 1° C. to 75° C., 1° C. to 100°C., 5° C. to 500° C., 10° C. to 1000° C., 20° C. to 200° C., 50° C. to500° C., 75° C. to 1000° C., or 100° C. to 1000° C.

In some embodiments, the first polymer is characterized by a storagemodulus that is at least 10 MPa greater than the second polymer, atleast 20 MPa greater than the second polymer, at least 50 MPa greaterthan the second polymer, at least 100 MPa greater than the secondpolymer, at least 200 MPa greater than the second polymer, at least 300MPa greater than the second polymer, at least 400 MPa greater than thesecond polymer, at least 500 MPa greater than the second polymer, atleast 10 MPa less than the second polymer, at least 20 MPa less than thesecond polymer, at least 50 MPa less than the second polymer, at least100 MPa less than the second polymer, at least 200 MPa less than thesecond polymer, at least 300 MPa less than the second polymer, at least400 MPa less than the second polymer, or at least 500 MPa less than thesecond polymer.

In some embodiments, a fracture strain or an elongation to break is theratio between the change in length and the initial length after breakageof a composition. In certain embodiments, the fracture strain provides ameasure of the capacity of the composition to be deformed using anexternal force. In certain embodiments, a first polymer is characterizedby an elongation to break that is differs from the elongation to breakof a second polymer by more than 2%, by more than 5%, by more than 10%,by more than 15%, by more than 25%, by more than 30%, by more than 40%,by more than 50%, by more than 60%, by more than 70%, by more than 80%,by more than 90%, or by more than 95%.

In some embodiments, the composite material has greater than 30%transparency, greater than 40% transparency, greater than 50%transparency, greater than 60% transparency, greater than 70%transparency, greater than 80% transparency, greater than 90%transparency, or greater than 95% transparency. In preferredembodiments, the composite material has greater than 80% transparency.

In some embodiments, stress relaxation can be measured by monitoring thetime-dependent stress resulting from a steady strain. The extent ofstress relaxation can also depend on the temperature and moisture.

The dynamic viscosity of a fluid indicates its resistance to shearingflows. The SI unit for dynamic viscosity is the Poiseuille (Pa·s).Dynamic viscosity is commonly given in units of centipoise, where 1centipoise (cP) is equivalent to 1 mPa·s. Kinematic viscosity is theratio of the dynamic viscosity to the density of the fluid; the SI unitis m²/s. Devices for measuring viscosity include viscometers andrheometers.

Composite Layers from a Single Resin

In certain embodiments, the composite material can be used to createappliances. As a non-limiting example, a dental appliance can be createdusing the composite materials disclosed herein. FIG. 1 illustrates anexemplary orthodontic appliance 106 and jaw 104 including a patient'steeth. FIG. 2 illustrates orthodontic appliance cross-section 118 astaken along line 1C-1C of FIG. 1 . The orthodontic appliance 106 may bedesigned to fit over a number of teeth present in an upper or lower jaw.An exemplary orthodontic device may be manufactured as disclosed by themethods discussed herein. As illustrated, the orthodontic appliance hasa U-shaped cross-section to form one or more cavities for placement of apatient's teeth therein. The methods provided herein may be used toprint the dental appliance, thus affording it high modulus strength andlow elasticity. For example, techniques disclosed herein may be used tomanufacture orthodontic appliances similar to those presented in USPatent Application Publication 2015/0004553, the disclosure of which isincorporated herein by reference in its entirety

A composite material having a high modulus and low elasticity cangenerate the force needed to move teeth, while a composite materialhaving a low modulus and high elasticity material to give the compositematerial both good mouth feel and low breakage. Finding a singlematerial that has both of these properties is very difficult, and usinga 3D printable resin with these two contrasting capabilities has notbeen possible to date. In certain embodiments, a stereolithographic 3Dprinter is used to obtain a material that behaves like a compositematerial by using reactivity differences of two or more differentmonomers, which then leads to 3D-spatially controlled compositionaldifferences.

Mechanical properties of a material or structure of the appliance (e.g.,stiffness, elongation, tensile strength, compressive strength, bendingproperties, viscoelastic properties, etc.) may be anisotropic, such thatthe properties are different when measured along x, y, and z directions.By changing the directionality of the structures, materials of anappliance, and/or source of radiation, varying properties can bedeveloped along different directions (e.g., mesial-distal direction,occlusal-gingival direction, buccal-lingual direction,anterior-posterior direction, interior-exterior direction). Suchvariations in directionality can be achieved using the directfabrication methods described herein, such as 3D printing.

In some embodiments, appliances with variable localized properties arepresented herein and are produced by direct fabrication. The directfabrication techniques presented herein may be particularly suited formanufacturing of appliances with different localized properties thatwould otherwise be difficult to achieve with other fabrication methods(e.g., indirect fabrication methods such as thermoforming a materialsheet over a mold). For instance, in some embodiments, the directfabrication techniques herein are used to fabricate appliancesexhibiting variable thicknesses, variable stiffnesses, and/or variablematerial compositions at different portions of the appliance. Forexample, variable material compositions can be varied monomer componentconcentration present in printed appliance, wherein the composite isformed from a single resin. Additional description of direct fabricationmethods suitable for producing the appliances of the present disclosureare provided further herein.

In some embodiments, the manufacture of a composite material derivedfrom a single resin comprises single Vat, digital light processing(DLP), stereolithographic 3D printing, photocured material jetting,photocured fused deposition modeling (FDM), a hybrid thereof, or acombination thereof. In certain embodiments, the process uses lightintensity to direct where one material of the composite forms relativeto a second material in the composite. In some embodiments, the processof using light intensity to direct the formation of material in thecomposition also allows for the creation of different patterns oftensile strength and modulus within the material, such as an orthodonticappliance. In some embodiments, the process directs compositionaldifferences in both vertical and horizontal dimensions. In certainembodiments, the composite material disclosed herein could be made froma standard thermoplastic composite. The process may direct phaseseparation in both vertical and horizontal dimensions.

Common current orthodontic appliance materials include composites thatuse a high modulus (low elongation) material sandwiched between two highelongation (low modulus) materials. This configuration allows theoverall material to provide enough force (from the high modulusmaterial) to move teeth, but does not break when inserting or removing(from the high elongation material).

Attempts to create a material with these characteristics (high modulusand high elongation) in a homogenous material have been less than idealin at least some aspects. Creating homogenous materials is difficult dueto stress relaxation in high humidity environments. The traditionalapproach is to use hydrogen bonding to obtain a tough material (highmodulus and high elongation), however, in moist environments, hydrogenbonded materials lose their toughness and will show increased stressrelaxation. Attempts to create a 3D printable resin that is tough havealso used hydrogen bonding; and consequently have provided similar highstress relaxation.

Thus, it is desirable to create a composite structure on a 3D printer toobtain a tough material that does not require hydrogen bonding. Thematerial may include hydrogen bonding if desired. In some embodiments,the composite material is obtained by first choosing at least twodifferent types of monomers components that have different reactivities.In a non-limiting example, Monomer 1 prefers to react with itself morethan with Monomer 2, but Monomer 2 also reacts preferentially withMonomer 1. Additionally, Monomer 1 and Monomer 2 are able to polymerizewith a reasonable rate to make them applicable for 3D printing. Theresulting mixture is more likely to polymerize Monomer 1 when exposed toconditions which promote polymerization, such as exposure to light and aphotoinitiator.

In some embodiments, Monomer 1 and Monomer 2 comprise more than one typeof monomer. As a non-limiting example, monomer 1 can be a methacrylateand monomer 2 can be a mixture of thiol and allyl ether components. Inthis example, the methacrylate tends to react first, then the thiol-ene(the allyl ether and thiol) will copolymerize. Photoinitiators andthermal initiators, or other forms of catalysts or reactive species maybe used separately or combined to initiate polymerization of monomer 1and/or monomer 2.

In some embodiments, the monomers are monofunctional. In certainembodiments, the monomers have a plurality of functionalities. Incertain embodiments, the monomers are difunctional. In some embodiments,the monomers are trifunctional.

In another embodiment, monomer 1 is an acrylate and monomer 2 is amethacrylate. The two monomers are mixed and a photoinitiator is added.The resin is then placed in a vat of a top down 3D printer. The choicefor any given layer is a single exposure to create a homogenous materialor multiple exposures per layer to create a composite material in thatlayer.

In some embodiments, the photoinitiation of the polymerization reactionuses a mask or other mechanism for forming a patterned light shield fora portion of the polymerizable resin comprising monomer 1 and monomer 2.While the mask is present, an exposure of light will cause the monomer 1to preferentially polymerize in the exposed areas. During and after theexposure, monomer 1 from areas directly adjacent to the exposed areawill diffuse into the exposed area and react as long as radicals orother reactive species or catalysts are still present or are beinggenerated. Monomer 2 will be diluted by this process and in some caseseven diffuse counter to monomer 1. The result is that the first exposuregenerates a polymer that is has a higher incorporation of monomer 1 thanof monomer 2. A second exposure can then be applied. The second exposuremay be to the entire polymerizable solution, to a different masked area(with or without overlap of the first masked area) or may use adifferent condition to induce polymerization, such as using heat toinduce thermal polymerization. In the second exposure, some regions willhave a higher concentration of monomer 2 than the starting resin due tothe diffusion caused by the first exposure, and the polymer that formsin those regions will have a greater incorporation of monomer 2.Accordingly, a single layer may have regions of polymer composed mostlyof monomer 1, and regions of polymer composed mostly of monomer 2. Insome embodiments, the resulting polymer composition comprises an evenmix of monomer 1 and monomer 2, which may occur if the regions are toodistant form the first exposed region for diffusion to affect themonomer concentrations. For example, resins using more than two monomerscan allow for creation of regions in the layer that differ inconcentration for all monomers added to the resin formulation andpolymerized into a composite material.

Manufacturing Techniques and Applications

In certain embodiments, a composite may be created having a plurality oflayers, wherein different layers within the plurality have differentproperties (FIG. 3 ). In an exemplary embodiment, a build platform isobtained having a print area as depicted in FIG. 4 . A homogenous resincomprising equal parts of monomer 1 and monomer 2 is positioned on thebuild platform, and is then exposed to an unmasked source of radiation,thus initiating polymerization to form a copolymer without diffusion(FIG. 4 , central panel). This first layer polymer is composed equallyof monomer 1 and monomer 2. A second layer of the resin is positioned ontop of the first layer, and monomer 1 is preferentially polymerized bythe source of radiation in a plurality of regions, with the aid of amasking pattern (FIG. 4 , right panel). The resulting composite material1 has a polymer composed of a majority of monomer 1. Due to diffusion,the regions not exposed to the source of radiation are comprised mostlyof monomer 2. A second exposure of the second layer uses a maskingpattern that is the opposite of the first pattern used (FIG. 5 , leftpanel), and is exposed to the source of radiation to form a secondpolymer incorporating mostly monomer 2. Accordingly, the second layercontains a composite material comprising a polymer mostly composed ofmonomer 1 and a second polymer mostly composed of monomer 2. A thirdlayer is positioned on top of the second layer (FIG. 5 , central panel),and monomer 1 is preferentially polymerized by the source of radiationin a plurality of regions, with the aid of a masking pattern. Due todiffusion, the majority of monomer 2 moves to regions that have not yetbeen exposed to the source of radiation. Following removal of themasking device, the entire platform is exposed to the source ofradiation, resulting in the polymerization of monomer 2 into a polymercomprising of mostly monomer 2 (FIG. 5 , right panel). The followingexposure is a blanket exposure and cures all the areas previouslyexposed in addition to areas not exposed. The areas next to thepreviously exposed regions will contain a higher concentration ofmonomer 2 and will thus form a polymer preferentially incorporatingmonomer 2. Accordingly, the third layer contains a composite materialcomprising a polymer mostly composed of monomer 1 and a second polymermostly composed of monomer 2. A fourth layer is positioned on top of thethird layer (FIG. 6 , left panel), and monomer 1 is preferentiallypolymerized by the source of radiation in a plurality of regions, withthe aid of a masking pattern. The unpolymerized monomer can either bedrained, polymerized by other means such as thermal treatment, or leftinside the layer as liquid pockets. Later treatments can infuse a newmaterial if desired. A fifth layer of resin is positioned on top of thefourth layer (FIG. 6, center panel), and the entire platform is exposed,thus forming a polymer comprising nearly equal portions of monomer 1 andmonomer 2. Finally, a sixth layer of resin is positioned on top of thefifth layer (FIG. 6 , right panel). A low intensity radiation is used topreferentially polymerize monomer 1 near the top of the layer. Diffusionof monomers 1 and 2 results in a gradient formation. Accordingly, layer6 comprises polymers having a majority of monomer 1 near the top of theZ-axis, and polymers having a majority of monomer 2 near the bottom ofthe Z-axis (FIG. 6 , right panel, FIG. 7 ). The exposure is dimmed incomparison to the exposures used for the other layers causingpreferential polymerization to occur at the surface (in the direction ofthe light) and diffusion to occur away from the surface.

For any given layer, one or a plurality of exposures can be used. Eachexposure can be slow or fast, and can be of variable intensities foreach exposure. In certain embodiments, top down or bottom up 3D printersthat use light to polymerize resin can be used. In certain embodiments,the methods herein use printers, such as the AutoDesk Ember, the Gizmo3D printer, Octave printers, Full Spectrum Laser 3D printers, Inkjet 3Dprinters, stereolithographic 3D printers, and the like. Inkjet 3Dprinters are capable of creating composite materials but are generallylimited on the resolution that is obtained compared tostereolithographic type of 3D printers.

In certain embodiments, monomer 1 and monomer 2 are partially misciblewith each other. In preferred embodiments, monomer 1 and monomer 2 arefully miscible with each other. In some embodiments, monomer 2 ispartially or fully immiscible in polymer 1, wherein polymer 1 is apolymer formed from a majority of monomer 1. Counter diffusion ofmonomer 2 is enhanced if monomer 2 is partially or fully immiscible inPolymer 1. In some embodiments, it is desirable to have a first exposurefor a layer to form a polymer primarily composed of monomer 1 and thenmove to the next layer, thus leaving only a structure composed primarilyof polymer of monomer 1. In some embodiments, it is desirable to varythe composition of formed polymer in the z dimension in addition to orindependent of the x and y dimensions by using the methods taught inU.S. Pat. No. 8,921,447, which is hereby incorporated by reference.

In some embodiments, processes described herein may be influenced by afirst region created from a first polymer comprising a majority ofmonomer 1. In some embodiments the first region is influenced by boththe wavelength of light and by the diffusion rates of the monomers. Incertain embodiments, the lower bound for the smallest dimension of thecomposite structures is governed by the light source. As a non-limitingexample, when using a laser, the width of a laser beam at its focus canachieve dimension sizes of 10s of nanometers to microns. Smallerdimension sizes are achievable in some embodiments wherein two photontechniques or holography is used. In some embodiments digital lightprocessing (DLP) projectors are used, and they can be limited by theinherent resolution of the projectors, which typically give X-Yresolutions of greater than 20 microns. In more typical embodiments, DLPprojectors give X-Y resolutions of greater than 50 microns. In someembodiments, the diffusion rate of either monomer 1, monomer 2, thelight intensity, the temperature, or a combination thereof govern theupper bound in the smallest obtainable dimensional size of the compositestructures. Factors that influence the diffusion rate includetemperature, size of the monomers, viscosity, shape of the monomers, andother molecular factors. Fast diffusion corresponds with the ability tocreate larger structures in a reasonable amount of time. In preferredembodiments, structure sizes range from 10's of nanometers to 500microns in the X-Y dimensions. In certain embodiments, the Z dimensionis governed by the motor and drive mechanism used to move the buildplatform and typically is larger than 1 micron. In some embodiments, theZ dimension is greater than 10 nm, greater than 20 nm, greater than 30nm, greater than 50 nm, greater than 100 nm, greater than 200 nm,greater than 250 nm, greater than 500 nm, greater than 750 nm, greaterthan 1 micron, greater than 2 microns, greater than 3 microns, greaterthan 4 microns, greater than 5 microns, greater than 10 microns, greaterthan 20 microns, greater than 30 microns, greater than 50 microns,greater than 75 microns, greater than 100 microns, greater than 200microns, greater than 300 microns, greater than 500 microns, greaterthan 750 microns, or greater than 1 mm. In some embodiments, the Zdimension is from 0.01 nm to 10 nm, from 0.1 nm to 10 nm, from 0.5 nm to10 nm, from 0.1 nm to 1 nm, from 1 nm to 10 nm, from 1 nm to 20 nm, from1 nm to 30 nm, from 1 nm to 50 nm, from 1 nm to 100 nm, from 1 nm to 200nm, from 1 nm to 250 nm, from 1 nm to 500 nm, from 1 nm to 750 nm, from1 nm to 1 micron, from 1 nm to 2 microns, from 1 nm to 3 microns, from 1nm to 4 microns, from 1 nm to 5 microns, from 1 nm to 10 microns, from 1nm to 20 microns, from 1 nm to 30 microns, from 1 nm to 50 microns, from1 nm to 75 microns, from 1 nm to 100 microns, from 1 nm to 200 microns,from 1 nm to 300 microns, from 1 nm to 500 microns, from 1 nm to 750microns, or from 1 nm to 1 mm.

In certain embodiments, a holographic pattern is used to create lightand dark regions during exposure to the source of radiation. Inpreferred embodiments, a holographic projector is utilized to activateholograms for 3D printing. With advanced calculations, an object can beprinted using a holographic image of the object in a volume of liquidwithout the need for printing layers. In addition, since holographicimages are interference patterns, they are already composed of light anddark regions on a nanometer scale. Since diffusion is faster on smallspatial scales, the intensity of the light can be higher and the layeris created faster than if larger light and dark regions are used.

In some embodiments, the processes disclosed herein create a materialwith a planar composite structure with alternating layers of highmodulus and high elongation materials, including composite structuresuseful in orthodontic appliances. Additionally, the tensile orcompressional force can be adjusted in different regions of theorthodontic appliance as desired.

Outside of the orthodontic field, other applications may benefit fromthe processes and techniques described herein. Having the ability tocreate a composite material that is spatially defined out of a singleresin is a large step forward and opens the possibility of 3D circuitsincluding the use of conductive and nonconductive materials, datastorage, structural materials, shape changing materials, spatiallycontrolled ceramics, and a whole host of other uses.

In some embodiments, the present disclosure describes applications thatmay be applied to aerospace engineering. A composite material may beformed from a single resin comprising materials that are advantageous touse in aerospace applications. As a non-limiting example, a compositematerial comprising monomer or polymer compositions and furthercomprising ceramics may provide increased strength modulus. Compositematerials can be beneficial to aerospace applications, such aselectromagnetic shielding, provide improved tribological properties, andproviding improved coatings. In some embodiments, the resultingcomposite material provides a lightweight alternative to conventionalmaterials. In certain embodiments, the production of the compositematerial provides an affordable alternative to conventional materials.In certain embodiments, a resin comprising monomer components canfurther comprise a clay. In some embodiments, a resin comprising a clayor ceramic can undergo polymerization to form a polymer matrix embeddedwith the clay or ceramic. In certain embodiments, the resin comprisesceramic nanocomposites, and the resulting composite material alsocomprises ceramic nanocomposites.

All references cited throughout this application, for example patentdocuments including issued or granted patents or equivalents; patentapplication publications; and non-patent literature documents or othersource material; are hereby incorporated by reference herein in theirentireties, as though individually incorporated by reference, to theextent each reference is at least partially not inconsistent with thedisclosure in this application (for example, a reference that ispartially inconsistent is incorporated by reference except for thepartially inconsistent portion of the reference).

The terms and expressions which have been employed herein are used asterms of description and not of limitation, and there is no intention inthe use of such terms and expressions of excluding any equivalents ofthe features shown and described or portions thereof, but it isrecognized that various modifications are possible within the scope ofthis disclosure. Thus, it should be understood that although the presentdisclosure has been specifically disclosed by preferred embodiments,exemplary embodiments and optional features, modification and variationof the concepts herein disclosed may be resorted to by those skilled inthe art, and that such modifications and variations are considered to bewithin the scope of this disclosure as defined by the appended claims.The specific embodiments provided herein are examples of usefulembodiments of the present disclosure and it will be apparent to oneskilled in the art that the present disclosure may be carried out usinga large number of variations of the devices, device components, methodssteps set forth in the present description. As will be obvious to one ofskill in the art, methods and devices useful for the present methods caninclude a large number of optional composition and processing elementsand steps.

When a group of substituents is disclosed herein, it is understood thatall individual members of that group and all subgroups, including anyisomers, of the group members, are disclosed separately. When a Markushgroup or other grouping is used herein, all individual members of thegroup and all combinations and subcombinations possible of the group areintended to be individually included in the disclosure. When a compoundis described herein such that a particular isomer, for example, in aformula or in a chemical name, that description is intended to includeeach isomers a of the compound described individual or in anycombination. Additionally, unless otherwise specified, all isotopicvariants of compounds disclosed herein are intended to be encompassed bythe disclosure. For example, it will be understood that any one or morehydrogens in a molecule disclosed can be replaced with deuterium ortritium. Isotopic variants of a molecule are generally useful asstandards in assays for the molecule and in chemical and biologicalresearch related to the molecule or its use. Methods for making suchisotopic variants are known in the art. Specific names of compounds areintended to be exemplary, as it is known that one of ordinary skill inthe art can name the same compounds differently.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural reference unless thecontext clearly dictates otherwise. Thus, for example, reference to “acell” includes a plurality of such cells and equivalents thereof knownto those skilled in the art, and so forth. As well, the terms “a” (or“an”), “one or more” and “at least one” can be used interchangeablyherein. It is also to be noted that the terms “comprising”, “including”,and “having” can be used interchangeably. The expression “of any ofclaims XX-YY” (wherein XX and YY refer to claim numbers) is intended toprovide a multiple dependent claim in the alternative form, and in someembodiments is interchangeable with the expression “as in any one ofclaims XX-YY.”

Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art to which this disclosure belongs. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present disclosure, the preferred methodsand materials are now described. Nothing herein is to be construed as anadmission that the invention is not entitled to antedate such disclosureby virtue of prior invention.

Every formulation or combination of components described or exemplifiedherein can be used to practice this disclosure, unless otherwise stated.

Whenever a range is given in the specification, for example, atemperature range, a pressure range, a modulus range, or a compositionor concentration range, all intermediate ranges and subranges, as wellas all individual values included in the ranges given are intended to beincluded in the disclosure. As used herein, ranges specifically includethe values provided as endpoint values of the range. For example, arange of 1 to 100 specifically includes the end point values of 1 and100. It will be understood that any subranges or individual values in arange or subrange that are included in the description herein can beexcluded from the claims herein.

As used herein, “comprising” is synonymous with “including,”“containing,” or “characterized by,” and is inclusive or open-ended anddoes not exclude additional, unrecited elements or method steps. As usedherein, “consisting of” excludes any element, step, or ingredient notspecified in the claim element. As used herein, “consisting essentiallyof” does not exclude materials or steps that do not materially affectthe basic and novel characteristics of the claim. In each instanceherein any of the terms “comprising”, “consisting essentially of” and“consisting of” may be replaced with either of the other two terms. Thedisclosure illustratively described herein suitably may be practiced inthe absence of any element or elements, limitation or limitations whichis not specifically disclosed herein.

One of ordinary skill in the art will appreciate that startingmaterials, biological materials, reagents, synthetic methods,purification methods, analytical methods, assay methods, and biologicalmethods other than those specifically exemplified can be employed in thepractice of this disclosure without resort to undue experimentation. Allart-known functional equivalents, of any such materials and methods areintended to be included in this disclosure. The terms and expressionswhich have been employed are used as terms of description and not oflimitation, and there is no intention that in the use of such terms andexpressions of excluding any equivalents of the features shown anddescribed or portions thereof, but it is recognized that variousmodifications are possible within the scope of this disclosure. Thus, itshould be understood that although the present disclosure has beenspecifically disclosed by preferred embodiments and optional features,modification and variation of the concepts herein disclosed may beresorted to by those skilled in the art, and that such modifications andvariations are considered to be within the scope of this disclosure asdefined by the appended claims.

While preferred embodiments of the present disclosure have been shownand described herein, it is to be understood that the disclosure is notlimited to the particular embodiments of the disclosure described below,as variations of the particular embodiments are made and still fallwithin the scope of the appended claims. It is also to be understoodthat the terminology employed is for the purpose of describingparticular embodiments of the disclosure, and is not intended to belimiting. Instead, the scope of the present disclosure is established bythe appended claims. In this specification and the appended claims, thesingular forms “a,” “an” and “the” include plural reference unless thecontext clearly dictates otherwise.

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the preferred embodiments of the presentdisclosure only and are presented in the cause of providing what isbelieved to be the most useful and readily understood description of theprinciples and conceptual embodiments of various embodiments of thedisclosure. In this regard, no attempt is made to show structuraldetails of the disclosure in more detail than is necessary for thefundamental understanding of the disclosure, the description taken withthe drawings and/or examples making apparent to those skilled in the arthow the several forms of the disclosure are embodied in practice.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how tomake and use the present disclosure and are not intended to limit thescope of what is regarded as the disclosure nor are they intended torepresent that the experiments below are all or the only experimentsperformed. Efforts have been made to ensure accuracy with respect tonumbers used (e.g., amounts, temperature, etc.) but some experimentalerrors and deviations should be accounted for. Unless indicatedotherwise, parts are parts by weight, molecular weight is weight averagemolecular weight, temperature is in degrees Centigrade, and pressure isat or near atmospheric.

Example 1 Composite Layer Comprising Dogbone Pattern

This Example describes a method of creating a composite material,wherein a dogbone shaped pattern is used to create regions ofpolymerization in the resultant composition. A dogbone pattern comprisestwo large shoulders and a gage section in between (see FIG. 9A). Acomparison is made between full exposure of each dogbone-shaped regionwith the use of a mask to create a plurality of lines.

A resin was created by mixing tricyclodecane diacrylate (1 gram),isobornyl acrylate (3 grams), Exothane 8 (4 grams), Irgacure 819 (0.096gram), and AIBN (0.088 gram). The resin was mixed vigorously until allreagents were fully dissolved.

A portion of the resin was placed between two glass slides with a500-micrometer spacer, thereby forming a 500-micrometer layer of resin(“Sample 1”). Using the resin, this step was repeated in order to formSample 2 and Sample 3.

A dogbone pattern was projected onto the samples, as depicted in FIG.9A. Sample 1 was masked using a plain dogbone pattern (FIG. 9A, bottom).Sample 2 was masked using a dogbone pattern having lines that wereparallel to the long axis of the dogbone (FIG. 9A, center). Sample 3 wasmasked using a dogbone pattern having lines that were perpendicular tothe long axis of the dogbone (FIG. 9A, top). Each sample was cured usingan Acer H6510BD DLP projector (Model H1P117) light for 5 minutes. Thesamples were then exposed for a second time using just the blank dogbone(no pattern), curing any uncured regions from the first exposure. Thenthe excess uncured liquid was poured out of the slides and all threesamples were heated to 100° C. for 15 minutes. The samples were thenremoved from the glass slide sandwich and cleaned with isopropanol,dried, and allowed to sit 24 hours before testing.

The composite materials were each tested and characterized (Table 1).

TABLE 1 Comparison of dogbone patterning and dogbone patterning withstripes Characterization Sample 1 Sample 2 Sample 3 Young's modulus  830MPa  850 MPa  997 MPa Transition temperature Tg 90° C. 88° C. 92° C.Elongation to yield  7%  8%  8% Elongation to break 19% 40% 32% Storagemodulus 1700 MPa 1800 MPa 2100 MPa Storage modulus at 70° C.  526 MPa 490 MPa  570 MPa

The material in Sample 1 was a homogenous polymer material composed ofboth monomer 1 and monomer 2, and is an example of localized bulk cure.In Sample 2, a composite material with alternating lines of polymercomprised mostly of the methacrylate polymer was formed, runningparallel to the long axis of the dogbone due to the exposure regionprovided by the mask. The elongation to break character of Sample 2 wasmore than double that of Sample 1 (see: FIG. 9B, FIG. 9C). Sample 3 wasalso a composite material with alternating lines of polymer comprisedmostly of the methacrylate polymer, but the lines ran perpendicular tothe long axis of the dogbone due to the exposure region provided by themask. The elongation to break character of Sample 3 was higher than thatof Sample 1, but less than Sample 2 (FIG. 9D). This result shows thatthe direction of exposure patterning can play an important role in theresulting composite materials.

Example 2 Composite Layer Comprising Dogbone Pattern Mask

This Example describes a method of creating a composite material,wherein a vertical patterning material is used to increase elongationwhen compared to the bulk cured material.

A resin comprising a hard phase (31 wt. % isobornyl methacrylate and10.7 wt. % bisphenol A dimethacrylate), a semi-hard phase that ties thetwo monomer systems together (17.9 wt. % tert-butylacrylate), a softhard phase (31.9 wt. % vinyl propionate and 5.1 wt. % vinyl laurate),and an initiator system (2.1 wt. % TPO-L and 1% AIBN) was mixed untilall reagents were fully resolved.

A portion of the resin was placed between two glass slides with a500-micrometer spacer, thereby forming a 500-micrometer layer of resin.A first layer of resin was cured with a 50-micrometer grating pattern. Asecond layer of resin was formed in the same manner, and was curedwithout a micrometer grating pattern. The layers were cured using 1 mWlight at 400 nm for 10 minutes. The pattern was removed, and bothsamples were further cured with irradiation for an additional 5 minutesat 50 mW, then heated to 100° C. for 1 hour.

The fully exposed film was removed from the glass slides, and dog boneshapes were cut from the material to test on a tensile tester. The bulkpolymer material without patterned exposure comprised a homogenousmixture of components, and had a Young's modulus of 1500 MPa, and anelongation to yield of 3%.

In comparison, the polymer material with patterned exposure comprised50-micron wide regions rich in methacrylate, because the methacrylatecured first to form a copolymer with the acrylate. The patternalternated with 50-micron wide regions rich in vinyl ester, because thevinyl ester tended to cure last to form a copolymer with the acrylate.Dog bone shapes were cut from the material to test on a tensile tester.The patterned exposure had a Young's modulus of 1400 MPa, and anelongation to yield of 8%.

Example 3 Cationic Curing System

This Example describes a method of curing a polymer composite materialusing cationic curing.

A resin comprising a hard phase (48.7 wt. % Omnilane OC 1005, anepoxide), a soft phase (49.6 wt. % isobutyl vinyl ether), and a cationicinitiator system (1 wt. % iodonium salt, 0.7 wt. % 9-vinyl carbazole)was mixed until all reagents were fully dissolved.

A portion of the resin was placed between two glass slides with a500-micrometer spacer, thereby forming a 500-micrometer layer of resin.A first layer of resin was cured with a 50-micrometer grating pattern. Asecond layer of resin was formed in the same manner, and was curedwithout a micrometer grating pattern. The layers were cured using 1 mWlight at 380 nm for 10 minutes. The pattern was removed, and bothsamples were further cured with irradiation for an additional 5 minutesat 50 mW, then heated to 100° C. for 1 hour.

The fully exposed film was removed from the glass slides, and dog boneshapes were cut from the material to test on a tensile tester. The bulkmaterial without patterned exposure had turned white due to phaseseparation between the polyvinyl ether and the epoxide monomer.

During the second light exposure, the dark areas of the patterned filmwere cured. If left alone, the dark areas will cure without the secondlight exposure due to cationic polymerization, which will be cured withdiffusion by the reactive cation. As the spacing between the gratingpattern decreased from 100 micrometers to 10 micrometers, samples becameobservably clearer, and were also easier to handle. Accordingly, smalliterations of patterning throughout the system generated a more robustproduct.

Example 4 Formation of an Interpenetrating Network

This Example describes a method of forming an interpenetrating network.Interpenetrating networks typically allow for phase separation byseparation of cure mechanisms.

A resin comprising an acrylate phase (39.5 wt. % tert-butyl acrylate,5.9 wt. % isodecyl acrylate (Photomer 4810), 1.9 wt. % tricyclodecanediacrylate), an epoxy-anhydride phase (22 wt. % Omnilane 1005, 26 wt. %hexahydro-4-methylphthalic anhydride), a free radical photoinitiator(1.5 wt. % TPO-L), and a thermal epoxy-anhydride catalyst (3.2 wt. %)was mixed until all reagents were fully dissolved.

A portion of the resin was placed between two glass slides with a500-micrometer spacer, thereby forming a 500-micrometer layer of resin.A first layer of resin was cured with a 50-micrometer grating pattern. Asecond layer of resin was formed in the same manner, and was curedwithout a micrometer grating pattern. The layers were cured using 1 mWlight at 380 nm for 10 minutes. The pattern was removed, and bothsamples were further cured with irradiation for an additional 5 minutesat 50 mW, then heated to 100° C. for 1 hour. The second blanket-exposureensured the acrylate was fully polymerized.

The fully exposed film was removed from the glass slides, and dog boneshapes were cut from the material to test on a tensile tester. The bulkmaterial without patterned exposure had turned white due to phaseseparation between the polyacrylate and the epoxy-anhydride oligomers.

The patterned exposed film was removed from the glass slides, and hadalso turned white. A comparison of patterns revealed that samples wereless brittle as the pattern size decreased. All samples showed amicrophase separation, even in areas undergoing initial irradiation.Accordingly, the epoxy-anhydride species did not have time to diffuseaway from the irradiated regions before being trapped in the acrylatemix. A better separation of materials is possible using a smaller lightpattern and/or a lower light intensity with more crosslinking of theacrylate.

Example 5 Comparison of Masked and Non-Masked Patterned Light

This Example describes a method of forming different polymer compositematerials using patterned masked and direct pattern light.

A resin comprising a vinyl ester phase (35 wt. % vinyl tert-butylbenzoate, 15 wt. % divinyl adipate), an acrylate phase (40 wt. %tert-butyl acrylate, 8.75 wt. % isodecyl acrylate), and initiators (2wt. % TPO-L, 0.25 wt. % AIBN) was mixed until all reagents were fullydissolved.

A portion of the resin was placed between two glass slides with a500-micrometer spacer, thereby forming a 500-micrometer layer of resin.A first layer of resin was cured with a 50_10 mask pattern, whereby 5micrometers of light and 10 micrometers of dark were used as the maskingpattern. The layer was cured using 0.2 mW light at 365 nm for 10minutes. The mask pattern was then removed and the layer was irradiatedan additional 5 minutes at 1 mW at 100° C. The first layer was thenheated to 100° C. for an additional hour. The first layer was removedfrom the glass slide and dog bones were cut from the material to test ona tensile tester.

A second layer of resin was formed in the same manner, and was patterneddirectly using a light source (i.e., no patterning mask was used). Theinterference pattern was generated from a 405 nm laser and a Lyod'smirror arrangement set at a 5-micrometer interference pattern. Thesecond layer was cured with the patterned light at 0.2 mW and 365 nm for10 minutes. The full layer was then irradiated for 5 minutes at 1 mW at100° C. The second layer was then heated to 100° C. for an additionalhour. The second layer was removed from the glass slide and dog boneswere cut from the material to test on a tensile tester.

A third layer of resin was formed in the same manner, and was exposedwithout pattern to a first light exposure using 0.2 mW at 365 nm for 10minutes. The third layer was then further irradiated for 5 minutes at 1mW at 100° C. The third layer was then heated to 100° C. for anadditional hour. The third layer was removed from the glass slide anddog bones were cut from the material to test on a tensile tester.

The masked patterned exposure at the vertical pattern (parallel to thegauge length) had a Young's modulus of 1515 MPa, an elongation to yieldof 25%, and a strength of 39 MPa. The direct pattern light using a laserpattern at the vertical pattern (parallel to the gauge length) had aYoung's modulus of 1420 MPa, an elongation to yield of 20%, and astrength of 40 MPa. The material obtained by mixed bulk cure (thirdlayer) had a Young's modulus of 1380 MPa, an elongation to yield of 16%,and a strength of 41 MPa.

As can be seen with the optical images of each layer (FIG. 8A, FIG. 8B),both patterns produce a clear optical pattern that is created in thematerial from refractive index differences between the exposed and thedark regions. The inset Raman heat maps indicate about a 10% enrichmentof acrylate in the first irradiated region, and about a 10% enrichmentof the vinyl ester in what was the dark region in the first irradiation.The difference in spatial composition is sufficient to create a materialwith properties that are distinct from the material obtained by mixedbulk cure.

An optical image of the first layer (the masked pattern) is displayed inFIG. 8A, and the inset displays a Raman heat map of the sample. Thelighter-colored bars display the thinner (approximately 5-micrometersthick) lines comprising an enriched population of acrylate, while theparallel darker bars display the thicker (approximately 10-micrometersthick) regions comprising an enriched population of the vinyl ester.Similarly, FIG. 8B displays an optical image of the second layer (thelaser pattern), and the inset displays a Raman heat map of the sample.As above, the lighter-colored lines display an enriched population ofacrylate, while the parallel darker bars display the regions comprisingan enriched population of the vinyl ester.

What is claimed is:
 1. A method for fabricating an orthodontic applianceconfigured to reposition a patient's teeth, the method comprising:providing a polymerizable composition, the polymerizable compositionincluding a first polymerizable component and a second polymerizablecomponent, the polymerizable composition characterized by an initialratio of the first polymerizable component to the second polymerizablecomponent; and fabricating a portion of the orthodontic appliance fromthe polymerizable composition by: forming a first region of theorthodontic appliance by exposing the polymerizable composition toradiation, wherein the first region includes a first ratio of the firstpolymerizable component to the second polymerizable component, the firstratio being different from the initial ratio, and forming a secondregion of the orthodontic appliance, wherein the second region includesa second ratio of the first polymerizable component to the secondpolymerizable component, the second ratio being different from theinitial ratio and the first ratio.
 2. The method of claim 1, wherein thepolymerizable composition comprises a resin.
 3. The method of claim 1,wherein the first polymerizable component comprises one or more of amethacrylate monomer, an acrylate monomer, a thiol monomer, a vinylacetate monomer, a styrene monomer, or a vinyl ether monomer.
 4. Themethod of claim 1, wherein the second polymerizable component comprisesone or more of an acrylate monomer, a thiol monomer, an allyl ethermonomer, a vinyl acetate monomer, a vinyl chloride monomer, anacrylonitrile monomer, a vinyl ether monomer, a vinyl silane monomer, avinyl siloxane monomer, a butadiene monomer, a norbornene, a maleatemonomer, a fumarate monomer, an epoxide monomer, an anhydride monomer,or a hydroxyl monomer.
 5. The method of claim 1, wherein the portion ofthe orthodontic appliance is fabricated via an additive manufacturingprocess.
 6. The method of claim 5, wherein the additive manufacturingprocess comprises building the portion of the orthodontic appliance froma plurality of layers.
 7. The method of claim 1, wherein the radiationcomprises light.
 8. The method of claim 1, wherein forming the firstregion of the orthodontic appliance comprises selectively exposing thefirst region to the radiation.
 9. The method of claim 8, wherein thefirst region is selectively exposed to the radiation using one or moreof a mask, a cover, a lens, or a filter.
 10. The method of claim 1,wherein exposing the polymerizable composition to the radiation causesphase separation in the polymerizable composition.
 11. A method forfabricating an orthodontic appliance configured to reposition apatient's teeth, the method comprising: providing a polymerizablecomposition, the polymerizable composition including a firstpolymerizable component and a second polymerizable component, thepolymerizable composition characterized by an initial ratio of the firstpolymerizable component to the second polymerizable component; andfabricating a portion of the orthodontic appliance by applying radiationto the polymerizable composition, wherein the portion of the orthodonticappliance comprises: a first region including a first ratio of the firstpolymerizable component to the second polymerizable component, the firstratio being different from the initial ratio, and a second regionincluding a second ratio of the first polymerizable component to thesecond polymerizable component, the second ratio being different fromthe initial ratio and the first ratio.
 12. The method of claim 11,wherein the polymerizable composition comprises a liquid.
 13. The methodof claim 11, wherein the first polymerizable component comprises one ormore of a methacrylate monomer, an acrylate monomer, a thiol monomer, avinyl acetate monomer, a styrene monomer, or a vinyl ether monomer. 14.The method of claim 11, wherein the second polymerizable componentcomprises one or more of an acrylate monomer, a thiol monomer, an allylether monomer, a vinyl acetate monomer, a vinyl chloride monomer, anacrylonitrile monomer, a vinyl ether monomer, a vinyl silane monomer, avinyl siloxane monomer, a butadiene monomer, a norbornene, a maleatemonomer, a fumarate monomer, an epoxide monomer, an anhydride monomer,or a hydroxyl monomer.
 15. The method of claim 11, wherein the portionof the orthodontic appliance is fabricated via a direct fabricationprocess.
 16. The method of claim 15, wherein the direct fabricationprocess comprises one or more of the following: a stereolithographictechnique, a digital light processing technique, a continuous liquidinterface production technique, a micro-stereolithographic technique, atwo photon polymerization technique, or a material jetting technique.17. The method of claim 11, wherein the radiation comprises light. 18.The method of claim 11, wherein the radiation is applied in a patterncorresponding to the first and second regions.
 19. The method of claim11, wherein the radiation is selectively applied to the first region.20. The method of claim 11, wherein applying the radiation to thepolymerizable composition causes phase separation in the polymerizablecomposition.